Complete genomic sequence of the lytic bacteriophage DT1 of Streptococcus thermophilus

Streptococcus thermophilus lytic bacteriophage DT1, isolated from a mozzarella whey, was characterized at the microbiological and molecular levels. Phage DT1 had an isometric head of 60 nm and a noncontractile tail of 260 x 8 nm, two major structural proteins of 26 and 32 kDa, and a linear double-stranded DNA genome with cohesive ends at its extremities. The host range of phage DT1 was limited to 5 of the 21 S. thermophilus strains tested. Using S. thermophilus SMQ-301 as a host, phage DT1 had a burst size of 276 +/- 36 and a latent period of 25 min. The genome of phage DT1 contained 34,820 bp with a GC content of 39.1%. Forty-six open reading frames (ORFs) of more than 40 codons were found and putative functions were assigned to 20 ORFs, mostly in the late region of phage DT1. Comparative genomic analysis of DT1 with the completely sequenced S. thermophilus temperate phage O1205 revealed two large homologous regions interspersed by two heterologous segments. The homologous regions consisted of the early replication genes, the late morphogenesis genes, and the lysis cassette. The divergent segments contained the DNA packaging machinery, the major structural proteins, and remnants of a lysogeny module.     

Genome sequence analysis of the Vibrio parahaemolyticus lytic bacteriophage VPMS1

VPMS1 is a Vibrio parahaemolyticus lytic phage isolated from a marine clam. The 42.3-kb genome was predicted to encode 53 proteins. Comparison of the VPMS1 DNA genome with known phage genomes revealed no similarity; hence, it represents a new VP phage, organized into three differently oriented modules. The module for packaging covers 12 % of the genome, the module for structure covers 31 %, and the module for replication and regulation covers 48 %. The G + C content was 44.67 %. The coding region corresponds to 91 % of the genome, and 9 % apparently does not encode any protein. Thirty genes, constituting 57 % of the genome, had significant similarity to some reported proteins in the protein database; 23 genes, constituting 43 % of the genome, showed no significant homology to any reported protein, and these could be new proteins whose hypothetical functions can be deduced from their position in the genome.     

Complete genomic nucleotide sequence and analysis of the temperate bacteriophage VWB

The entire double-stranded DNA genome of the Streptomyces venezuelae bacteriophage VWB was sequenced and analyzed. Its size is 49,220 bp with an overall molar G + C content of 71.2 mol%. Sixty-one potential open reading frames were identified and annotated using several complementary bioinformatics tools. Clusters of functionally related putative genes were defined, supporting a refined version of the modular theory of phage evolution.     

Complete genomic sequence analysis of the temperate bacteriophage phiSASD1 of Streptomyces avermitilis

The bacteriophage phiSASD1, isolated from a failed industrial avermectin fermentation, belongs to the Siphoviridae family. Its four predominant structural proteins, which include the major capsid, portal and two tail-related proteins, were separated and identified by SDS-PAGE and N-terminal sequence analysis. The entire double-stranded DNA genome of phiSASD1 consists of 37,068 bp, with 3'-protruding cohesive ends of nine nucleotides. Putative biological functions have been assigned to 24 of the 43 potential open reading frames. Comparative analysis shows perfect assembly of three “core” gene modules: the morphogenesis and head module, the tail module and the right arm gene module, which displays obvious similarity to the right arm genes of Streptomyces phage phiC31 in function and arrangement. Meanwhile, structural module flexibility within phiSASD1 suggests that assignment of phage taxonomy based on comparative genomics of structural genes will be more complex than expected due to the exchangeability of functional genetic elements.     

Complete genome sequence of the lytic cold-active Pseudomonas fluorescens bacteriophage VSW-3 from Napahai plateau wetland

Virus Genes - The lytic cold-active bacteriophage VSW-3, belonging to the Podoviridae family and infecting the host Pseudomonas fluorescens SW-3, was isolated from the Napahai plateau wetland in...     

The complete genomic sequence of lytic bacteriophage gh-1 infecting Pseudomonas putida--evidence for close relationship to the T7 group

The genome of the lytic Pseudomonas putida bacteriophage gh-1 is linear double-stranded DNA containing 37,359 bp with 216-bp direct terminal repeats. Like other members of the T7 group, the gh-1 genome contains regions of high homology to T7 interspersed with nonhomologous regions that contain small open reading frames of unknown function. The genome shares 31 genes in common with other members of the T7 group, including RNA polymerase, and an additional 12 unique putative genes. A major difference between gh-1 and other members of this group is the absence of any open reading frames between the left direct terminal repeat and gene 1. Sequence analysis of the gh-1 genome also revealed the presence of 10 putative phage promoters with a consensus sequence similar to the promoters of T3 and phiYeO3-12 (consensus: TAAAAACCCTCACTRTGGCHSCM). P. putida mutants resistant to gh-1 were demonstrated to have an altered lipopolysaccharide structure, indicating that members of this group use lipopolysaccharide as their cellular receptor.     

Complete genomic sequence of the temperate bacteriophage PhiAT3 isolated from Lactobacillus casei ATCC 393

The complete genomic sequence of a temperate bacteriophage PhiAT3 isolated from Lactobacillus (Lb.) casei ATCC 393 is reported. The phage consists of a linear DNA genome of 39,166 bp, an isometric head of 53 nm in diameter, and a flexible, noncontractile tail of approximately 200 nm in length. The number of potential open reading frames on the phage genome is 53. There are 15 unpaired nucleotides at both 5' ends of the PhiAT3 genome, indicating that the phage uses a cos-site for DNA packaging. The PhiAT3 genome was grouped into five distinct functional clusters: DNA packaging, morphogenesis, lysis, lysogenic/lytic switch, and replication. The amino acid sequences at the NH2-termini of some major proteins were determined. An in vivo integration assay for the PhiAT3 integrase (Int) protein in several lactobacilli was conducted by constructing an integration vector including PhiAT3 int and the attP (int-attP) region. It was found that PhiAT3 integrated at the tRNAArg gene locus of Lactobacillus rhamnosus HN 001, similar to that observed in its native host, Lb. casei ATCC 393.     

Complete genomic sequence of the Lactobacillus temperate phage LF1

Bacteriophage LF1, a newly isolated temperate phage from a mitomycin-C-induced lysate of wild type Lactobacillus fermentum, was found to contain a double-strand DNA of 42,606 base pairs (bp) with a G+C content of 45%. Bioinformatic analysis of the phage genome revealed 57 putative open reading frames (ORFs). The predicted protein products of ORFs were determined and described. According to morphological analysis by transmission electron microscopy (TEM), LF1 has an isometric head and a non-contractile tail, indicating that it belongs to the family Siphoviridae. The temperate phage LF1 has a good genetic mosaic relationship with ΦPYB5 in the packaging module. To our knowledge, this is first report of genomic sequencing and characterization of temperate phage LF1 from wild-type L. fermentum isolated from Kimchi in Korea.     

Complete genome sequence of virulent bacteriophage SHOU24, which infects foodborne pathogenic Vibrio parahaemolyticus

A novel lytic Vibrio parahaemolyticus phage (SHOU24) belonging to the family Siphoviridae was isolated from aquatic market sewage. The phage is only able to infect V. parahaemolyticus containing a tdh gene. SHOU24 has a linear genome of 77,837 bp with a G+C content of 46.0 %. In total, 88 predicted proteins have homologues in databases, and the majority of the core genes share high sequence similarity with genes from unrelated viruses and bacteria. Genes related to lysogeny and host lysis were not detected. However, the detection method, the results of a one-step growth experiment and analysis using the Phage Classification Tool Set (PHACTS) indicate that SHOU24 is lytic. A bioinformatics analysis showed that SHOU24 is not closely related to other Vibrio phages.     

Complete nucleotide sequence and genome analysis of bacteriophage BFK20--a lytic phage of the industrial producer Brevibacterium flavum

The entire double-stranded DNA genome of bacteriophage BFK20, a lytic phage of the Brevibacterium flavum CCM 251--industrial producer of L-lysine--was sequenced and analyzed. It consists of 42,968 base pairs with an overall molar G + C content of 56.2%. Fifty-five potential open reading frames were identified and annotated using various bioinformatics tools. Clusters of functionally related putative genes were defined (structural, lytic, replication and regulatory). To verify the annotation of structural proteins, they were resolved by 2D gel electrophoresis and were submitted to N-terminal amino acid sequencing. Structural proteins identified included the portal and major and minor tail proteins. Based on the overall genome sequence comparison, similarities with other known bacteriophage genomes include primarily bacteriophages from Mycobacterium spp. and some regions of Corynebacterium spp. genomes--possible prophages. Our results support the theory that phage genomes are mosaics with respect to each other.     

Complete genomic sequence of turkey coronavirus

Turkey coronavirus (TCoV), one of the least characterized of all known coronaviruses, was isolated from an outbreak of acute enteritis in young turkeys in Ontario, Canada, and the full-length genomic sequence was determined. The full-length genome was 27,632 nucleotides plus the 3' poly(A) tail. Two open reading frames, ORFs 1a and 1b, resided in the first two thirds of the genome, and nine additional downstream ORFs were identified. A gene for hemagglutinin-esterase was absent in TCoV. The region between the membrane (M) and nucleocapsid (N) protein genes contained three potential small ORFs: ORF-X, a previously uncharacterized ORF with an associated putative TRS within the M gene (apparently shared among all group III coronaviruses), and previously described ORFs 5a and 5b. The TCoV genome is organized as follows: 5' UTR--replicase (ORFs 1a, 1b)--spike (S) protein--ORF3 (ORFs 3a, 3b)--small envelop (E or 3c) protein--membrane (M) protein--ORF5 (ORFs X, 5a, 5b)--nucleocapsid (N) protein--3' UTR--poly(A). TCoV genome structure and sequence was most similar, but distinct from, avian infectious bronchitis virus (IBV). This is the first complete genome sequence for a TCoV and confirms that TCoV belongs to group III coronaviruses.     

Complete genome sequence of marine bacterium Pseudoalteromonas phenolica bacteriophage TW1

For molecular study of marine bacteria Pseudoalteromonas phenolica using bacteriophage, a novel bacteriophage, TW1, belonging to the family Siphoviridae, was isolated, and its genome was completely sequenced and analyzed. The phage TW1 genome consists of 39,940-bp-length double-stranded DNA with a GC content of 40.19 %, and it was predicted to have 62 open reading frames (ORFs), which were classified into functional groups, including phage structure, packaging, DNA metabolism, regulation, and additional function. The phage life style prediction using PHACTS showed that it may be a temperate phage. However, genes related to lysogeny and host lysis were not detected in the phage TW1 genome, indicating that annotation information about P. phenolica phages in the genome databases may not be sufficient for the functional prediction of their encoded proteins. This is the first report of a P. phenolica-infecting phage, and this phage genome study will provide useful information for further molecular research on P. phenolica and its phage, as well as their interactions.     

Complete genome sequence analysis of bacterial-flagellum-targeting bacteriophage chi

Bacteriophage chi is a well-known phage that infects pathogens such as E. coli, Salmonella, and Serratia via bacterial flagella. To further understand its host-phage interaction and infection mechanism via host flagella, the genome was completely sequenced and analyzed. The phage genome contains 59,407-bp-length DNA with a GC content of 56.51 %, containing 75 open reading frames (ORFs) with no tRNA genes. Its annotation and functional analysis revealed that chi is evolutionarily very closely related to Enterobacter phage Enc34 and Providencia phage Redjac. However, most of the annotated genes encode hypothetical proteins, indicating that further genomic study of phage chi is required to elucidate the bacterial-flagellum-targeting infection mechanism of phage chi.     

Complete genome sequence of the Pectobacterium carotovorum subsp. carotovorum virulent bacteriophage PM1

PM1, a novel virulent bacteriophage that infects Pectobacterium carotovorum subsp. carotovorum, was isolated. Its morphological features were examined by electron microscopy, which indicated that this phage belongs to the family Myoviridae. It has a 55,098-bp genome, including a 2,665-bp terminal repeat. A total of 63 open reading frames (ORFs) were predicted, but only 20 ORFs possessed homology with functional proteins. There is one tRNA coding region, and the GC-content of the genome is 44.9 %. Most ORFs in bacteriophage PM1 showed high homology to enterobacteria phage ΦEcoM-GJ1 and Erwinia phage νB EamM-Y2. Like these bacteriophages, PM1 encodes an RNA polymerase, which is a hallmark of T7-like phages. There is no integrase or repressor, suggesting that PM1 is a virulent bacteriophage.     

Complete genomic DNA sequence of rock bream iridovirus

Iridovirus is a causative agent of epizootics among cultured rock bream (Oplegnathus fasciatus) in Korea. Here, we report the complete genomic sequence of rock bream iridovirus (RBIV). The genome of RBIV was 112080 bp long and contained at least 118 putative open reading frames (ORFs), and its genome organization was similar to that of infectious spleen and kidney necrosis virus (ISKNV). Of the RBIV's 118 ORFs, 85 ORFs showed 60-99% amino acid identity to those of ISKNV. Phylogenetic analysis of major capsid protein (MCP), DNA repair protein RAD2, and DNA polymerase type-B family indicated that RBIV is closely related to red sea bream iridovirus (RSIV), Grouper sleepy disease iridovirus (GSDIV), Dwarf gourami iridovirus (DGIV), and ISKNV. The genome sequence provides useful information concerning the evolution and divergence of iridoviruses in cultured fish.     

Complete genomic sequence of bacteriophage ul36: demonstration of phage heterogeneity within the P335 quasi-species of lactococcal phages

The complete genomic sequence of the Lactococcus lactis virulent phage ul36 belonging to P335 lactococcal phage species was determined and analyzed. The genomic sequence of this lactococcal phage contained 36,798 bp with an overall G+C content of 35.8 mol %. Fifty-nine open reading frames (ORFs) of more than 40 codons were found. N-terminal sequencing of phage structural proteins as well as bioinformatic analysis led to the attribution of a function to 24 ORFs (41%). A lysogeny module was found within the genome of this virulent phage. The putative integrase gene seems to be the product of a horizontal transfer because it is more closely related to Streptococcus pyogenes phages than it is to L. lactis phages. Comparative genome analysis with six complete genomes of temperate P335-like phages confirmed the heterogeneity among phages of P335 species. A dUTPase gene is the only conserved gene among all P335 phages analyzed as well as the phage BK5-T. A genetic relationship between P335 phages and the phage-type of the BK5-T species was established. Thus, we proposed that phage BK5-T be included within the P335 species and thereby reducing the number of lactococcal phage species to 11.     

Complete genome sequence of Escherichia coli O157:H7 lytic phage JL1

A novel virulent phage named JL1 against Escherichia coli O157:H7 was isolated from raw sewage. It was found that JL1 has an icosahedral head and a long flexible non-contractile tail. The complete genome of JL1 is composed of a linear double-stranded DNA of 43,457 base pairs in length, with 54.77 % G+C content and 60 putative open reading frames. Morphology and bioinformatics analysis revealed that phage JL1 is a member of the family Siphoviridae of the order Caudovirales. It is different from previously reported phages of E. coli O157:H7 but is homologous to Sodalis phage SO-1, Shigella phage EP23, Escherichia phage HK578 and Escherichia phage SSL-2009a.