Bacteriophage Genome Sequences Research Articles

Basic Guidelines for Bacteriophage Isolation and Characterization.

The world is on the cusp of a post-antibiotic period. A century ago, before the advent of antibiotics, bacteriophage therapy was the treatment of choice for bacterial infections. Although bacteriophages have yet to be approved as a treatment in Western medicine, researchers and clinicians have begun to anticipate phage therapy. Bacteriophages are viruses that depend on bacterial cell metabolism to multiply. They offer a promising alternative to the use of antibiotics and an excellent antibacterial option for combating multidrug resistance in bacteria. However, not every phage is suitable for phage therapy. In particular, prophages should not be used because they can lysogenize host cells instead of lysing them. To offer adequate therapeutic options for patients suffering from various infectious diseases, a wide selection of different phages is needed. While there is no evidence of direct toxicity induced by phage particles, it is crucial to study mammalian cell-phage interactions. This requires phage preparations to be free of bacterial cells, toxins and other compounds to avoid skewing host responses. Negative staining of purified viruses and electron microscopy remain the gold standard in the identification of bacteriophages. Interestingly, genomics has greatly changed our understanding of phage biology. Bacteriophage genome sequencing is essential to obtain a complete understanding of the bacteriophages' biology and to obtain confirmation of their lifestyle. Full genetic sequencing of bacteriophage will enable a better understanding of the phage-encoded proteins and biomolecules (especially phage lytic enzymes) involved in the process of bacterial cell lysis and death. Mass spectrometry can be used for the identification of phage structural proteins. The use of lytic phages as biocontrol agents requires the most appropriate and standard methods to ensure application safety. This review pursues recent research and methods in molecular biology for the isolation and characterization of phages to facilitate follow-up and implementation of work for other researchers. Patents related to this topic have been mentioned in the text.

Identification of bacteriophage genome sequences with representation learning.

MotivationBacteriophages/phages are the viruses that infect and replicate within bacteria and archaea, and rich in human body. To investigate the relationship between phages and microbial communities, the identification of phages from metagenome sequences is the first step. Currently, there are two main methods for identifying phages: database-based (alignment-based) methods and alignment-free methods. Database-based methods typically use a large number of sequences as references; alignment-free methods usually learn the features of the sequences with machine learning and deep learning models.ResultsWe propose INHERIT which uses a deep representation learning model to integrate both database-based and alignment-free methods, combining the strengths of both. Pre-training is used as an alternative way of acquiring knowledge representations from existing databases, while the BERT-style deep learning framework retains the advantage of alignment-free methods. We compare INHERIT with four existing methods on a third-party benchmark dataset. Our experiments show that INHERIT achieves a better performance with the F1-score of 0.9932. In addition, we find that pre-training two species separately helps the non-alignment deep learning model make more accurate predictions.Availability and implementationThe codes of INHERIT are now available in: https://github.com/Celestial-Bai/INHERIT.Supplementary information Supplementary data are available at Bioinformatics online.

Complete Genome Sequence Analysis of the Cold-active Siphoviridae Bacteriophage from Pseudomonas fluorescens

Phages are considered the most abundant and diverse biological entities on Earth. Although many phages have been isolated, most of this diversity remains completely unexplored. Recent advances in genome sequencing, however, have provided unprecedented glimpses into the virosphere. The lytic cold-active Siphoviridae bacteriophage VW6S, infecting the host Pseudomonas fluorescens W-6, was isolated from the Napahai plateau wetland in China. The newly sequenced phage VW6S contained double-stranded DNA with a genome size of 37,917 bp, an overall GC content of 56.90% and 52 open reading frames (ORFs). The genome was organized into several modules containing genes for packaging, structural proteins, replication/transcription, and cell lysis. The sequence contained 16 transcription terminators, no tRNAs. The lysis cassette of VW6S consisted of 4 proteins (holin protein, lysin protein and 2 putative spanins). This is the first report on cold-active SiphoviridaePseudomonas fluorescens bacteriophage genome sequencing.

Amplification for Whole Genome Sequencing of Bacteriophages from Single Isolated Plaques Using SISPA.

Genomics has greatly transformed our understanding of phage biology; however, traditional methods of DNA isolation for whole genome sequencing have required phages to be grown to high titers in large-scale preparations, potentially selecting for only those phages that can grow efficiently under laboratory conditions. This may also select for mutations or deletions that enable more efficient growth in culture. The ability to sequence a bacteriophage genome from a single isolated plaque reduces these risks while decreasing the time and complexityof bacteriophage genome sequencing. A method of amplification and library preparation is described, utilizing Sequence Independent Single Primer Amplification (SISPA), that can be used for whole genome shotgun sequencing of bacteriophages from a single isolated plaque.

Analyzing Genome Termini of Bacteriophage Through High-Throughput Sequencing.

High-throughput sequencing (HTS) is an effective tool for bacteriophage genome and its termini analysis. HTS technology parallelizes the sequencing process, producing thousands to millions of reads concurrently. Terminal information of a bacteriophage genome is important and basic knowledge for understanding the biology of the bacteriophage. We have created a high-occurrence reads as termini theory and developed practical methods to determine the bacteriophage genome termini, which is based on the large data of HTS. With this method, the termini of the bacteriophage genome can be efficiently and reliably identified as a by-product of bacteriophage genome sequencing, by solely analyzing the sequence statistics of the raw sequencing data (reads), without any further lab experiments.

Bacteriophage Genome Sequencing: A New Alternative to Understand Biochemical Interactions between Prokaryotic Cells and Phages

Bacteriophages are viruses or semi-autonomous genetic entities that depend on prokaryotic cell’s metabolism to multiply. The use of lytic phages as biocontrol agents in many fields such as food preservation, disease control, agriculture production signifies the need of most appropriate and standard methods to insure application safety. Bacteriophage full genetic material sequencing is a new alternative to better understand phage encoded proteins and biomolecules (especially phage lytic enzymes) involved in the process of bacterial cell lysis and death. Thus, this short review aimed to discuss sequencing importance applied to bacteria-phage interactions in society commercial sectors, focusing in the food industry.

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

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 China. With the development of sequencing technology, the study of Pseudomonas genomic diversity has increased; however, knowledge of cold-active phages infecting Pseudomonas is limited. The newly sequenced phage VSW-3 was classified based on virion morphology by transmission electron microscope. Sequence analysis revealed that the genome size was 40,556bp with an overall GC content of 57.54% and 46 open reading frames. The genome was organized into several modules containing genes for packaging, structural proteins, replication/transcription, and phage lysis. The sequence contained 45 potential promoters, 3 transcription terminators, and yet no tRNAs. This is the first report of cold-active Pseudomonas fluorescens bacteriophage genome sequencing.

Inferring bacteriophage infection strategies from genome sequence: analysis of bacteriophage 7-11 and related phages.

BackgroundAnalyzing regulation of bacteriophage gene expression historically lead to establishing major paradigms of molecular biology, and may provide important medical applications in the future. Temporal regulation of bacteriophage transcription is commonly analyzed through a labor-intensive combination of biochemical and bioinformatic approaches and macroarray measurements. We here investigate to what extent one can understand gene expression strategies of lytic phages, by directly analyzing their genomes through bioinformatic methods. We address this question on a recently sequenced lytic bacteriophage 7 - 11 that infects bacterium Salmonella enterica.ResultsWe identify novel promoters for the bacteriophage-encoded σ factor, and test the predictions through homology with another bacteriophage (phiEco32) that has been experimentally characterized in detail. Interestingly, standard approach based on multiple local sequence alignment (MLSA) fails to correctly identify the promoters, but a simpler procedure that is based on pairwise alignment of intergenic regions identifies the desired motifs; we argue that such search strategy is more effective for promoters of bacteriophage-encoded σ factors that are typically well conserved but appear in low copy numbers, which we also verify on two additional bacteriophage genomes. Identifying promoters for bacteriophage encoded σ factors together with a more straightforward identification of promoters for bacterial encoded σ factor, allows clustering the genes in putative early, middle and late class, and consequently predicting the temporal regulation of bacteriophage gene expression, which we demonstrate on phage 7-11.ConclusionsWhile MLSA algorithms proved highly useful in computational analysis of transcription regulation, we here established that a simpler procedure is more successful for identifying promoters that are recognized by bacteriophage encoded σ factor/RNA polymerase. We here used this approach for predicting sequence specificity of a novel (bacteriophage encoded) σ factor, and consequently inferring phage 7-11 transcription strategy. Therefore, direct analysis of bacteriophage genome sequences is a plausible first-line approach for efficiently inferring phage transcription strategies, and may provide a wealth of information on transcription initiation by diverse σ factors/RNA polymerases.

Improved Bacteriophage Genome Data is Necessary for Integrating Viral and Bacterial Ecology

The recent rise in "omics"-enabled approaches has lead to improved understanding in many areas of microbial ecology. However, despite the importance that viruses play in a broad microbial ecology context, viral ecology remains largely not integrated into high-throughput microbial ecology studies. A fundamental hindrance to the integration of viral ecology into omics-enabled microbial ecology studies is the lack of suitable reference bacteriophage genomes in reference databases-currently, only 0.001% of bacteriophage diversity is represented in genome sequence databases. This commentary serves to highlight this issue and to promote bacteriophage genome sequencing as a valuable scientific undertaking to both better understand bacteriophage diversity and move towards a more holistic view of microbial ecology.

The complete genome sequence of EC1-UPM, a novel N4-like bacteriophage that infects Escherichia coli O78:K80

BackgroundBacteriophage EC1-UPM is an N4-like bacteriophage which specifically infects Escherichia coli O78:K80, an avian pathogenic strain that causes colibacillosis in poultry. The complete genome sequence of bacteriophage EC1-UPM was analysed and compared with other closely related N4-like phage groups to assess their genetic similarities and differences.ResultsBacteriophage EC1-UPM displays a very similar codon usage profile with its host and does not contain any tRNA gene. Comparative genomics analysis reveals close resemblance of bacteriophage EC1-UPM to three N4-like bacteriophages namely vB_EcoP_G7C, IME11 and KBNP21 with a total of 44 protein coding genes shared at 70% identity threshold. The genomic region coding for the tail fiber protein was found to be unique in bacteriophage EC1-UPM. Further annotation of the tail fiber protein using HHpred, a highly sensitive homology detection tool, reveals the presence of protein structure homologous to various polysaccharide processing proteins in its C-terminus. Leveraging on the availability of multiple N4-like bacteriophage genome sequences, the core genes of N4-like bacteriophages were identified and used to perform a multilocus phylogenetic analysis which enabled the construction of a phylogenetic tree with higher confidence than phylogenetic trees based on single genes.ConclusionWe report for the first time the complete genome sequence of a N4-like bacteriophage which is lytic against avian pathogenic Escherichia coli O78:K80. A novel 928 amino acid residues tail fiber protein was identified in EC1-UPM which may be useful to further the understanding of phage-host specificity. Multilocus phylogenetic analysis using core genes of sequenced N4-like phages showed that the evolutionary relationship correlated well with the pattern of host specificity.

Multiplex PCR for the detection and identification of dairy bacteriophages in milk

Bacteriophage infections of starter lactic acid bacteria are a serious risk in the dairy industry. Phage infection can lead to slow lactic acid production or even the total failure of fermentation. The associated economic losses can be substantial. Rapid and sensitive methods are therefore required to detect and identify phages at all stages of the manufacture of fermented dairy products. This study describes a simple and rapid multiplex PCR method that, in a single reaction, detects the presence of bacteriophages infecting Streptococcus thermophilus and Lactobacillus delbrueckii, plus three genetically distinct ‘species’ of Lactococcus lactis phages commonly found in dairy plants (P335, 936 and c2). Available bacteriophage genome sequences were examined and the conserved regions used to design five pairs of primers, one for each of the above bacteriophage species. These primers were designed to generate specific fragments of different size depending on the species. Since this method can detect the above phages in untreated milk and can be easily incorporated into dairy industry routines, it might be readily used to earmark contaminated milk for use in processes that do not involve susceptible starter organisms or for use in those that involve phage-deactivating conditions.

The impact of bacteriophage genomics.

The discovery of (bacterio)phages revolutionised microbiology and genetics, while phage research has been integral to answering some of the most fundamental biological questions of the twentieth century. The susceptibility of bacteria to bacteriophage attack can be undesirable in some cases, especially in the dairy industry, but can be desirable in others, for example, the use of bacteriophage therapy to eliminate pathogenic bacteria. The relative ease with which entire bacteriophage genome sequences can now be elucidated has had a profound impact on the study of these bacterial parasites.