• Journal of Microbiology and Biotechnology
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• v.24 no.6
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• pp.740-747
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• 2014

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is a very serious disease in rice-growing regions of the world. In spite of their economic importance, there are no effective ways of protecting rice plants from this disease. Bacteriophages infecting Xoo affect the population dynamics of the pathogen and consequently the occurrence of the disease. In this study, we investigated the diversity, host range, and infectivity of Xoo phages, and their use as a bicontrol agent on BLB was tested. Among the 34 phages that were isolated from floodwater in paddy fields, 29 belonged to the Myoviridae family, which suggests that the dominant phage in the ecosystem was Myoviridae. The isolated phages were classified into two groups based on plaque size produced on the lawn of Xoo. In general, there was a negative relationship between plaque size and host range, and interestingly the phages having a narrow host range had low efficiency of infectivity. The deduced protein sequence analysis of htf genes indicated that the gene was not a determinant of host specificity. Although the difference in host range and infectivity depending on morphotype needs to be addressed, the results revealed deeper understanding of the interaction between the phages and Xoo strains in floodwater and damp soil environments. The phage mixtures reduced the occurrence of BLB when they were treated with skim milk. The results indicate that the Xoo phages could be used as an alternative control method to increase the control efficacy and reduce the use of agrochemicals.

• Journal of Microbiology
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• v.45 no.1
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• pp.58-63
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• 2007

In this study, the relative synonymous codon and amino acid usage biases of the broad-host range phage, KVP40, were investigated in an attempt to understand the structure and function of its proteins/protein-coding genes, as well as the role of its tRNAs. Synonymous codons in KVP40 were determined to be AT-rich at the third codon positions, and their variations are dictated principally by both mutational bias and translational selection. Further analysis revealed that the RSCU of KVP40 is distinct from that of its Vibrio hosts, V. cholerae and V. parahaemolyticus. Interestingly, the expression of the putative highly expressed genes of KVP40 appear to be preferentially influenced by the abundant host tRNA species, whereas the tRNAs expressed by KVP40 may be required for the efficient synthesis of all its proteins in a diverse array of hosts. The data generated in this study also revealed that KVP40 proteins are rich in low molecular weight amino acid residues, and that these variations are influenced primarily by hydropathy, mean molecular weight, aromaticity, and cysteine content.

• Journal of Microbiology
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• v.42 no.2
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• pp.99-102
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• 2004

Bacteriophage PM2 has a closed circular form of double stranded DNA as a genome. This DNA from the phage is a useful source for nick-circle endonuclease assay in the fmol range. Due to difficulties in the maintenance of viral infectivity, storage conditions of the phage should be considered for the puri-fication of PM2 DNA. The proper condition for a short-term storage of less than 2 months is to keep the PM2 phage at 4$^{\circ}C$; whereas the proper condition for a long-term storage of the PM2 phage for over 2 months is to keep it under liquid nitrogen in 7.5 ％ glycerol. The optimal conditions for a high yield of phage progeny were also considered with the goal to achieve a successful PM2 DNA preparation. A MOI(Multiplicity Of Infection) of 0.03, in which the OD$\sub$600/ of the host bacteria was between 0.3 and 0.5, turned out to be optimal for the mass production of PM2 phage with a burst size of about 214. Considerations of PM2 genome size, and the concentrations and radiospecific activities of purified PM2 DNA, are required to measure the endonuclease activity in the fmol range. This study reports the proper quantitation of radioactivity and the yield of purified DNA based on these conditions.

• Journal of Microbiology and Biotechnology
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• v.27 no.12
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• pp.2151-2155
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• 2017

Bacteriophages have gained substantial attention as biocontrol and biorecognition agents, substituting antibodies. In this study, a Salmonella Enteritidis-specific bacteriophage, KFS-SE1, was isolated, identified, and characterized. This Siphoviridae phage infects S. Enteritidis with high specificity. This phage is highly stable under various pH (5-11), temperature ($4-60^{\circ}C$), and organic solvent conditions. The KFS-SE1 genome consisted of 59,715 bp with 73 predicted open reading frames and 57.14% GC content; it had a complete set of genes required for phage reconstruction. Comparative phylogenetic analysis of KFS-SE1 revealed that it was very similar to the other Salmonella phages in the Siphoviridae family. These characteristics suggest that KFS-SE1 with its high specificity and host lysis activity toward S. Enteritidis may have various potential applications.

• Journal of Microbiology and Biotechnology
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• v.22 no.12
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• pp.1613-1620
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• 2012

Bacterial wilt caused by Ralstonia solanacearum is a devastating disease of many economically important crops. Since there is no promising control strategy for bacterial wilt, phage therapy could be adopted using virulent phages. We used phage PE204 as a model lytic bacteriophage to investigate its biocontrol potential for bacterial wilt on tomato plants. The phage PE204 has a short-tailed icosahedral structure and double-stranded DNA genome similar to that of the members of Podoviridae. PE204 is stable under a wide range of temperature and pH, and is also stable in the presence of the surfactant Silwet L-77. An artificial soil microcosm (ASM) to study phage stability in soil was adopted to investigate phage viability under a controlled system. Whereas phage showed less stability under elevated temperature in the ASM, the presence of host bacteria helped to maintain a stable phage population. Simultaneous treatment of phage PE204 at $10^8$ PFU/ml with R. solanacearum on tomato rhizosphere completely inhibited bacterial wilt occurrence, and amendment of Silwet L-77 at 0.1% to the phage suspension did not impair the disease control activity of PE204. The biocontrol activities of phage PE204 application onto tomato rhizosphere before or after R. solanacearum inoculation were also investigated. Whereas pretreatment with the phage was not effective in the control of bacterial wilt, post-treatment of PE204 delayed bacterial wilt development. Our results suggested that appropriate application of lytic phages to the plant root system with a surfactant such as Silwet L-77 could be used to control the bacterial wilt of crops.

• Korean Journal of Microbiology
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• v.25 no.3
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• pp.184-188
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• 1987

Evidences that the mannose permease of Escherichia coli mediates the infection of N4 in early steps, were obtained as follows. First, A mutant strain of Escherichia coli which was resistant to both wild type N4 and lambda whose genome is Charon 4A containing human genomic fragments in its EcoR I site, could not use mannose efficiently. Second, N4 could not infect pel mutant strains which lack one or all of intact components of mannose permease. However, unknown alterations in N4 made it possible for the phage to infect pel mutant of E. coli. It also turned out to be clear that the receptor of N4 was different from that of lambda.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1050-1056
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• 2023

Weizmannia coagulans (formerly Bacillus coagulans) is Gram-positive, and spore-forming bacteria causing food spoilage, especially in acidic canned food products. To control W. coagulans, we isolated a bacteriophage Youna2 from a sewage sludge sample. Morphological analysis revealed that phage Youna2 belongs to the Siphoviridae family with a non-contractile and flexible tail. Youna2 has 52,903 bp double-stranded DNA containing 61 open reading frames. There are no lysogeny-related genes, suggesting that Youna2 is a virulent phage. plyYouna2, a putative endolysin gene was identified in the genome of Youna2 and predicted to be composed of a N-acetylmuramoyl-L-alanine amidase domain (PF01520) at the N-terminus and unknown function DUF5776 domain (PF19087) at the C-terminus. While phage Youna2 has a narrow host range, infecting only certain strains of W. coagulans, PlyYouna2 exhibited a broad antimicrobial spectrum beyond the Bacillus genus. Interestingly, PlyYouna2 can lyse Gram-negative bacteria such as Escherichia coli, Yersinia enterocolitica, Pseudomonas putida and Cronobacter sakazakii without other additives to destabilize bacterial outer membrane. To the best of our knowledge, Youna2 is the first W. coagulans-infecting phage and we speculate its endolysin PlyYouna2 can provide the basis for the development of a novel biocontrol agent against various foodborne pathogens.

• Journal of Applied Biological Chemistry
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• v.62 no.3
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• pp.287-292
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• 2019

Pseudomonas tolaasii causes brown blotch disease on the oyster mushroom (Pleurotus ostreatus). Various pathogenic strains of P. tolaasii were isolated and divided into three subtypes, $P1{\alpha}$, $P1{\beta}$, and $P1{\gamma}$. For phage therapy, bacteriophages against to these subtype strains were applied to mushroom cultivation and very successful to prevent from the disease. In this study, bacteriophages were isolated against the representative strains of subtype pathogens and their polyclonal antibodies were synthesized to investigate structural relationship among capsid proteins of phages. Phage preparations over $10^{10}pfu/mL$ were injected to rabbit thigh muscle and polyclonal antibodies were obtained after three times of boost injection. Titers of the antibodies obtained were over $2{\times}10^7Ab/mL$ for the phage ${\phi}6264$, $1{\times}10^6Ab/mL$ for the phage ${\phi}HK2$, and $1{\times}10^7Ab/mL$ for the phage ${\phi}HK19$ and phage ${\phi}HK23$. High specific activities were observed between antibodies and the corresponding bacteriophages. Some cross-reactivities between the antibodies and non-corresponding bacteriophages were also measured. Antibody $Ab{\phi}6264$ inactivated all phages of $P1{\alpha}$ subtype and only phage ${\phi}HK16$ among $P1{\beta}$ subtype phages. Antibody $Ab{\phi}HK23$ of $P1{\gamma}$ subtype neutralized all phages of $P1{\beta}$ subtype as well as the phage ${\phi}HK23$, showing the widest phage-inactivation range. When the structural-similarity studies of phages were investigated by using phage antibodies, closeness obtained by phylogenetic analysis of 16S rRNA genes of pathogenic strains were quite different from that of polyclonal antibody-specific structural similarity of phage capsid proteins. In conclusion, there is weak correlation between the host strain specificity of bacteriophage and its capsid structural similarity measured by phage antibodies.

• Microbiology and Biotechnology Letters
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• v.13 no.3
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• pp.265-271
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• 1985

The classification of bacteriophage could be followed by several criteria. In this study three criteria were used for classification of Lactobacillus casei bacteriophag. In serological classification. antiserum was prepared by rabbit and used for classification. The inactivation effect of phage by antiserum was exponential and L. casei phage was classified in to three serological groups by inactivation rate (K-values). The Lac Y group was proved as a new serological group but the Lac J and Lac S group were shown the same results as previous reports. From the comparison of restriction enzyme pattern of phage DNA, Lac J group was divided into four sub-groups. According to the difference of host range, Lac J-II group was further subdivided into three groups. These results were shown that L. casei strains S-1 bacteriophage was classified into 8 sub-groups. The phage YK of Lac Y group was shown to consist of a icosahedral head about 95nm in diameter, a contractile tail about 150nm in length and 20nm in width. The tail of YK phage is composed of stacked disks(4nm repeat)and a hexagonal baseplate. The molecular weight of YK phage DNA was approximately 85.6 Mdalton.

• Journal of Microbiology and Biotechnology
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• v.23 no.8
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• pp.1147-1153
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• 2013

Pectobacterium carotovorum subsp. carotovorum (formerly Erwinia carotovora subsp. carotovora) is a plant pathogen that causes soft rot and stem rot diseases in several crops, including Chinese cabbage, potato, and tomato. To control this bacterium, we isolated a bacteriophage, PP1, with lytic activity against P. carotovorum subsp. carotovorum. Transmission electron microscopy revealed that the PP1 phage belongs to the Podoviridae family of the order Caudovirales, which exhibit icosahedral heads and short non-contractile tails. PP1 phage showed high specificity for P. carotovorum subsp. carotovorum, and several bacteria belonging to different species and phyla were resistant to PP1. This phage showed rapid and strong lytic activity against its host bacteria in liquid medium and was stable over a broad range of pH values. Disease caused by P. carotovorum subsp. carotovorum was significantly reduced by PP1 treatment. Overall, PP1 bacteriophage effectively controls P. carotovorum subsp. carotovorum.