Isolation, characterization, and complete genome sequence of vibrio phage KIT04, a novel lytic phage of the subfamily ermolyevavirinae.

Vibrio phage KIT04 was isolated from muscle tissue samples collected from a local market in Vietnam. KIT04 is a lytic phage that is specific to Vibrio parahaemolyticus. The one-step growth curve determined the burst size and latent period of 0.01 multiplicity of infection KIT04 in V. parahaemolyticus as approximately 156 plaque-forming units/bacterium and 45 min, respectively. Vibrio phage KIT04 has an approximately 76.4 ± 4.5 nm diameter icosahedral head and a tail length of approximately 159.5 ± 16.6 nm long tail. KIT04 significantly reduced V. parahaemolyticus ATCC 17802 in vitro. Complete genome analysis showed that KIT04 had a 114,933 bp dsDNA genome with 40.24% G + C content and 160 open reading frames (ORFs). However, the phage genome contained 24 tRNAs and no lysogeny-related genes. Moreover, five of the 160 ORFs encoded unique hypothetical proteins, indicating that KIT04 is a novel phage. Genomic comparison indicated that KIT04 is closely related to the Vibrio phages pVp-1 and VPT02. Further, phylogenetic analysis of the major tail proteins and whole genome supported the KIT04 classification into the subfamily Ermolyevavirinae. Our study describes a new candidate phage that could be used as a bioagent for controlling Vibrio pathogens.

Characterization and Complete Genomic Analysis of Vibrio Parahaemolyticus-Infecting Phage KIT05.

Vibrio parahaemolyticus is a bacterial pathogen in marine aquaculture systems and a major cause of food-borne illnesses worldwide. In the present study, Vibrio phage KIT05 was isolated from water collected from a shrimp farm in the Mekong Delta, Vietnam. It was characterized based on its morphology, growth curve, lytic properties, and genome sequence. Under the electron microscope, KIT05 particles had an icosahedral head with a diameter of 62.3 nm and a short tail of 24.1 nm. The one-step growth curve of KIT05 showed that its latency time was approximately 40 min and burst size was 18 plaque-forming units/cell. The genome of KIT05 comprises 50,628 bp with a GC content of 41.63%. It contains 60 open reading frames that are encoded within both strands and four tRNAs. The presence of direct terminal repeats of 130 bp at both ends of the KIT05 DNA was determined. According to phage morphology, genomic organization, and phylogeny analysis, Vibrio phage KIT05 was classified into the family Podoviridae. The genome annotation revealed that KIT05 had no virulent or lysogenic genes. This study may help identify a novel candidate for developing biocontrol agents for Vibrio parahaemolyticus.

Isolation, Characterisation and Complete Genome Sequence of a Tequatrovirus Phage, Escherichia phage KIT03, Which Simultaneously Infects Escherichia coli O157:H7 and Salmonella enterica.

Escherichia coli O157:H7 and Salmonella enterica subsp. enterica are the pathogens that frequently cause foodborne illness. Bacteriophage applications have been proposed as effective for preventing food contamination caused by these pathogenic bacteria. Escherichia phage KIT03 was isolated from the soil of a poultry farm in Kyoto, Japan. KIT03 can infect Escherichia coli O157:H7 and Salmonella enterica serotypes Choleraesuis and Enteritidis. One-step growth analysis revealed that KIT03 can propagate within its initial host (E. coli NBRC 3972), E. coli O157:H7 and S. Choleraesuis with an approximate burst size of 39, 51 and 37 phage particles per infected cell, respectively. The morphological type and genome annotation suggested that KIT03 belongs to the family Myoviridae, subfamily Tevenvirinae, genus Tequatrovirus. In vitro challenge tests demonstrated that KIT03 can lyse the tested bacteria and suppress their growth. Based on the susceptibility test and adsorption assay of KIT03 with E. coli K-12 BW25113 mutants, it was proposed that KIT03 may recognise and infect bacteria with a deficient outer core of lipopolysaccharides.

Genomic characterization of Ralstonia solanacearum phage ϕRS138 of the family Siphoviridae.

ϕRS138, a bacteriophage of the family Siphoviridae that lyses Ralstonia solanacearum, was isolated. The genomic DNA of ϕRS138 was 41,941 bp long with a GC content of 65.1 % and contained 56 putative open reading frames. The ϕRS138 genome could be divided into three regions based on similarities to other genomes: (1) a region containing genes encoding a putative transcriptional regulator and an integrase, similar to the prophage genes in Ralstonia solanacearum K60-1; (2) a region encoding proteins related to structural modules and virion morphogenesis, similar to genes in the Pseudomonas phages of the family Siphoviridae; and (3) a region highly similar to the genomes of other Ralstonia solanacearum strains.