• Journal of Microbiology and Biotechnology
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• v.14 no.4
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• pp.730-736
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• 2004

This study aims at characterizing the bacteriophages isolated from activated sludge performing enhanced biological phosphorous removal (EBPR) to understand the interactions between the phage-host system and bacterial community. Sixteen bacterial isolates (E1-E16) were isolated as host bacterial strains from EBPR activated sludge for phage isolation. Forty bacteriophages based on their plaque sizes (2 plaques on E4, 4 on E8, 11 on E10, 5 on E14, 18 on E16) were obtained from filtered supernatant of the EBPR activated sludge. Each bacteriophage did not make any plaque on bacterial strains tested in this study except on its own host bacterial strain, respectively, indicating that the bacteriophages are with narrow host specificity. However, fourteen of the forty bacteriophages obtained in this study lost their virulent ability even on their own host bacteria. All of the lytic phages showed similar one-step growth patterns and had long latent period (about 9 hours) to reproduce their phage particles in their host bacterial cells. On the other hand, their probable burst sizes (6 to 48 per host cell) were large enough to actively lyse their host bacterial cells. Therefore, it could be implied that bacteriophages are also important members of the microbial community in EBPR activated sludge, and lytic phages directly decrease the population size of their host bacterial groups in EBPR activated sludge by lysis.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.2
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• pp.125-132
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• 2003

Uzi fly (Exorista bombycis Louis) is one of the major larval endo-parasitoid of silkworm (Bombyx mori). It causes extensive damage to sericulture industry. The application of synthetic organic pesticides has tremendous impact on minimizing pest population but their overuse and frequent misuse and high sensitivity towards the silkworms, has forced the entomologists to search for alternatives to chemical control, which is safe to silkworm, environment and farm workers. Biological control continues to offer exciting possibilities for the control of fly pest population. It is environmentally safe alternative to chemical control and offering a long-term protection. Several potential hymenopteran parasitoids have been screened. Among successful natural enemies, Nesolynx thymus, Trichomalopsis apanteloctena, Trichopria sp., Brachymeria lasus, Pediobius sp., Spalangia sp., Spilomicrus karnatakensis and Dhirhinus sp. are important. It is essential to predict accurately the efficacy of these natural enemies in a new habitat prior to its introduction. The important desirable attributes of these potential parasitoids viz., host searching capacity, specificity, power of increase and fitness and adaptability of the parasitoid in new environment has been recorded. Results of the host parasitoid interaction indicate that the aging of the host function as a factor that influence the host finding efficiency of the parasitoid. It is highly scored with 15-20 hrs old pupa of the host. However, aging of the parasitoid does not significantly affect it. The sex ratio is female biased which is advantageous from biological control point of view, Biological suppression methods involving conservation and utilization of natural enemies have been discussed in detail.

• Journal of Microbiology
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• v.45 no.2
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• pp.133-138
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• 2007

This study addresses the susceptibility of Spodoptera frugiperda (Sf9 and Sf21), Trichoplusia ni (Hi5), and S. exigua (Se301) cells to the Bombyx mori nucleopolyhedrovirus (BmNPV). Although these cells have classically been considered nonpermissive to BmNPV, the cytopathic effect, an increase in viral yield, and viral DNA synthesis by BmNPV were observed in Sf9, Sf21, and Hi5 cells, but not in Se301 cells. Very late gene expression by BmNPV in these cell lines was also detected via ${\beta}-galactosidase$ expression under the control of the polyhedrin promoter. Sf9 cells were most susceptible to BmNPV in all respects, followed by Sf21 and Hi5 cells in decreasing order, while the Se301 cells evidenced no distinct viral replication. This particular difference in viral susceptibility in each of the cell lines can be utilized for our understanding of the mechanisms underlying the host specificity of NPVs.

• 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.

• Research in Plant Disease
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• v.22 no.4
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• pp.236-242
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• 2016

Bacterial wilt caused by Ralstonia solanacearum is one of the most devastating diseases in major Solanaceae crops. The pathogen is easily disseminated and survives for many years in plant farming system. Although chemicals are applied to control the disease, they are of limited efficacy and cause several problems. Therefore, the use of phage therapy has been suggested to control the disease as a biological agent. In this study, we discovered bacteriophages lysing diverse Ralstonia isolates from plant and soil samples obtained from the potato cultivated field in Jeju. Three times repeated pickings of plaques resulted in obtaining 173 single phages showing diverse spectrum of host-specificity. With the results, 12 core phages were selected and dendrogram was generated. Genetic diversity of the selected phages was also confirmed by AFLP (Amplified Fragment of Length Polymorphism) fingerprinting. The stability of the phages was investigated in various temperatures and various conditions of pH in vitro. The phages were stable at $16^{\circ}C-44^{\circ}C$ and pH 6-10. Morphological characterization of the phages revealed they were all classified into the Podoviridae, but had diverse head sizes. The results of this research will contribute to control the disease and further researches regarding genetic and molecular aspects will facilitate understanding phage and bacteria interaction.

• The Korean Journal of Mycology
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• v.46 no.4
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• pp.427-435
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• 2018

In this study, endophytic fungi were isolated from the surface-sterilized roots of Calanthe discolor and Cephalanthera longibracteata collected from the Chungnam, Jeju, Kyungnam and Chungbuk provinces in Korea. The morphological characteristics of the obtained isolates were examined and their sequences of the internal transcribed spacer (ITS) rDNA region were analyzed using the ITS1F and ITS4 primers for species identification. Leptodontidium orchidcola showed the highest species abundance and frequency among the isolated endophytic fungi. Additionally, the community analysis revealed a high specificity between the host plants and the endophytic fungal species.

• Microbiology and Biotechnology Letters
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• v.18 no.6
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• pp.633-639
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• 1990

The genes for cellulases of Pseudomonas sp. LBC505 and CYC10, potent cellulase complex-producing strains, were cloned in Escherichia coli with pUC19. Recombinant plasmids pLCl and pLC2 were isolated from transformants producing cellulase by Congo red staining, and their genes cloned were 0.7 kb and 4.6 kb HindIII fragments, respectively. The inserts of pLCl and pLC2 were hybridized to chromosomal DNAs digested with HindIII from Pseudomona~ sp. LBC505 and CYC10, respectively. Immunodiffusion assays revealed that pLC1-and pLC2-encoded cellulase showed similarity with that of host strains. About 24% of cellulase activity was observed in the extracellular fraction of E. coli carrying pLC1, and its activity was higher about 1.4 times than that of LBC505. The enzymatic properties of pLC1 and pLC2 encoded cellulase were the same as those of cellulase from host strains. HPLC analysis and substrate specificity showed that cellulases were the same as those of cellulase from host strains. HPLC analysis and substrate specificity showed that cellulases cloned were endocellulase.

• Proceedings of the Botanical Society of Korea Conference
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• 1998.07a
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• pp.10-18
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• 1998

For improvement of plants in disease resistance, it is most important to elucidate the mechanism to perceive and respond to the signal molecules of invaders. A model system with pea and its pathogen, Mycosphaerella pinodes, showed that the fungal elicitor induced defense responses in all plant species tested but that the suppressor of the fungus blocked or delayed the expression of defense responses and induced accessibility only in the host plant. In the world, many researchers believe that the pathogens` signals are recognized only on the receptors in the plasma membranes. Though we found that the ATPase and polyphosphoinositide metabolism in isolated plasma membranes responded to these fungal signals, we failed to detect specific actions of the suppressor in vitro on these plasma membrane functions. Recently, we found that ATPase (NTPases) and superoxide generating system in isolated cell wall were regulated by these fungal signals even in vitro, especially, by the suppressor in a strictly species-specific manner and also that the cell wall alone prepared an original defense system. The effects of both fungal signals on the isolated cell wall functions in vitro coincide perfectly with those on defense responses in vivo. In this treatise, we discuss the key role of the cell wall, which is plant-specific and the most exterior organelle, in determining host-parasite specificity and molecular target for improvement of plants.

• Journal of Microbiology and Biotechnology
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• v.26 no.2
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• pp.385-393
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• 2016

Pseudomonas syringae pv. actinidiae causes bacterial canker disease in kiwifruit. Owing to the prohibition of agricultural antibiotic use in major kiwifruit-cultivating countries, alternative methods need to be developed to manage this disease. Bacteriophages are viruses that specifically infect target bacteria and have recently been reconsidered as potential biological control agents for bacterial pathogens owing to their specificity in terms of host range. In this study, we isolated bacteriophages against P. syringae pv. actinidiae from soils collected from kiwifruit orchards in Korea and selected seven bacteriophages for further characterization based on restriction enzyme digestion patterns of genomic DNA. Among the studied bacteriophages, two belong to the Myoviridae family and three belong to the Podoviridae family, based on morphology observed by transmission electron microscopy. The host range of the selected bacteriophages was confirmed using 18 strains of P. syringae pv. actinidiae, including the Psa2 and Psa3 groups, and some were also effective against other P. syringae pathovars. Lytic activity of the selected bacteriophages was sustained in vitro until 80 h, and their activity remained stable up to 50℃, at pH 11, and under UV-B light. These results indicate that the isolated bacteriophages are specific to P. syringae species and are resistant to various environmental factors, implying their potential use in control of bacterial canker disease in kiwifruits.

• Mycobiology
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• v.50 no.6
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• pp.448-456
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• 2022

In this study, the roots and rhizosphere soil of Abies koreana and Taxus cuspidata were collected from sites at two different altitudes on Mt. Halla. Ectomycorrhizal fungi (EMF) were identified by Illumina MiSeq sequencing. The proportion of EMF from the roots was 89% in A. koreana and 69% in T. cuspidata. Among EMF in rhizosphere soils, the genus Russula was the most abundant in roots of A. koreana (p < 0.05). The altitude did not affect the biodiversity of EMF communities but influenced fungal community composition. However, the host plants had the most significant effect on EMF communities. The result of the EMF community analysis showed that even if the EMF were isolated from the same altitudes, the EMF communities differed according to the host plant. The community similarity index of EMF in the roots of A. koreana was higher than that of T. cuspidata (p < 0.05). The results show that both altitude and host plants influenced the structure of EMF communities. Conifers inhabiting harsh sub-alpine environments rely strongly on symbiotic relationships with EMF. A. koreana is an endangered species with a higher host specificity of EMF and climate change vulnerability than T. cuspidata. This study provides insights into the EMF communities, which are symbionts of A. koreana, and our critical findings may be used to restore A. koreana.