• The Plant Pathology Journal
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• v.35 no.5
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• pp.473-485
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• 2019

Kiwifruit (Actinidia spp.) is an economically important crop and a bacterial canker disease, caused by Pseudomonas syringae pv. actinidiae (Psa), is the most destructive disease in kiwifruit production. Therefore, prevent and control of the disease is a critical issue in kiwifruit industry worldwide. Unfortunately, there is no reliable control methods have been developed. Recently, interest in disease control using microbial agents is growing. However, kiwifruit microbiota and their roles in the disease control is mainly remaining unknown. In this study, we secured bacterial libraries from kiwifruit ecospheres (rhizosphere, endospere, and phyllosphere) and screened reliable biocontrol strains against Psa. As the results, Streptomyces racemochromogenes W1SF4, Streptomyces sp. W3SF9 and S. parvulus KPB2 were selected as anti-Psa agents from the libraries. The strains showed forcible antibacterial activity as well as exceptional colonization ability on rhizosphere or phyllosphere of kiwifruit. Genome analyses of the strains suggested that the strains may produce several anti-Psa secondary metabolites. Our results will contribute to develop biocontrol strains against the kiwifruit canker pathogen and the disease management strategies.

• Korean Journal of Environmental Agriculture
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• v.35 no.1
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• pp.72-78
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• 2016

BACKGROUND: Entomopathogenic fungi have been studied to develop for biological control agents as an alternative to chemical control agents in insect pest management. This investigated to determine the optimal culture conditions in ceramic balls for maximal sporulation of entomopathogenic fungi Beauveria bassiana M130 by use rice bran extract.METHODS AND RESULTS: METHODS AND RESULTS: A culture of entomopathogenic fungi for 12day on rice bran extract(1:8, w/v) incubated in ceramic matrix at 28℃. Natural zeolite ceramic ball was high production of 4.2×108 conidial/mL. The culture condition optimized initial pH, temperature, rice bran extract concentration, adhesives substance and concentration of NaCl, respectively. The high production of spore optimal conditions were temperature 28℃, initial pH 3, rice bran extract 3 mL, starch 33 g, 5 % NaCl and sopre suspension 7 mL, respectively.CONCLUSION: This study was carried out for the mass production of entomopathogenic fungi conidia recover rate 65% in matrix of natural zeolite ceramic ball, and to develop ingredient-used formulation of Beauveria bassiana M130 conidia for biological control agents.

• The Plant Pathology Journal
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• v.22 no.2
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• pp.107-114
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• 2006

The white cottony stem rot pathogen Sclerotinia scierotiorum was subjected to 70 different isolates of actinomycetes indigenous to Jordan as biological control agents. Forty of them demonstrated chitinase activity on crab shell chitin agay (CCA) media and they were segregated into three groups: 14 highly active, 12 moderately active, and 14 with low activity, with average clearing zones of (4.7-8.3), (3.7-4.3), and (2.3-3.3) mm surrounding colonies on CCA, respectively. Further, these isolates were able to inhibit radial mycelium growth of the pathogen and were categorized into three antagonistic groups: 13 strong, 13 moderate, and 14 weak antagonists, with antibiosis inhibition Bones of (32.0-45.7), (22.7-31.3), and (3.7-22.3) mm, respectively. High levels of chitinase activity of the isolates Ma3 (8.3 mm), Jul (7.7 mm), and Sa8 (7.7 mm) with their antagonistic activity against mycelium growth of 45.7, 44.3, and 40.7 mm were observed, respectively. These isolates exhibited fungicidal activity against sclevotia of S. sclerotiorum. On the other hand, isolates Na5, Aj3, and Aj2 that produced no chitinase showed fungistatic effect only.

• The Plant Pathology Journal
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• v.32 no.2
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• pp.145-156
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• 2016

Fusarium graminearum Schwabe causes Fusarium head blight (FHB), a devastating disease that leads to extensive yield and quality loss of wheat and other cereal crops. Twelve isolates of F. graminearum were collected from naturally infected spikes of wheat from Assiut Egypt. These isolates were compared using SRAP. The results indicated distinct genetic groups exist within F. graminearum, and demonstrated that these groups have different biological properties, especially with respect to their pathogenicity on wheat. There were biologically significant differences between the groups; with group (B) isolates being more aggressive towards wheat than groups (A) and (C). Furthermore, Trichoderma harzianum (Rifai) and Bacillus subtilis (Ehrenberg) which isolated from wheat kernels were screened for antagonistic activity against F. graminearum. They significantly reduced the growth of F. graminearum colonies in culture. In order to gain insight into biological control effect in situ, highly antagonistic isolates of T. harzianum and B. subtilis were selected, based on their in vitro effectiveness, for greenhouse test. It was revealed that T. harzianum and B. subtilis significantly reduced FHB severity. The obtained results indicated that T. harzianum and B. subtilis are very effective biocontrol agents that offer potential benefit in FHB and should be harnessed for further biocontrol applications. The accurate analysis of genetic variation and studies of population structures have significant implications for understanding the genetic traits and disease control programs in wheat. This is the first known report of the distribution and genetic variation of F. graminearum on wheat spikes in Assiut Egypt.

• The Korean Journal of Soil Zoology
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• v.10 no.1_2
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• pp.55-64
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• 2005

Predatory nematodes are ubiquitous and feed on soil microorganisms including plant parasitic nematodes. They reduce populations of plant parasitic nematodes in virtually all soils because of their constant association with plant parasitic nematodes in the rhizosphere. Predatory potential of several species of predacious nematodes, belonging to the orders Mononchida, Diplogasterida, Dorylaimida and Aphelenchida, have been studied in detail on plant parasitic nematodes but most of the studies were based on in vitro experiments. A review of progress on the use of predatory nematodes as biological control agents of plant parasitic nematodes reveals that advocacy for predatory nematodes dates back to the early $20^{th}$ century; nevertheless, their potential has begun to be studied in recent years. Information on the efficacy of predatory nematodes under field conditions is lacking; however, some predatory nematodes have given very promising results against plant parasitic nematodes. This article summarizes research progress to date on predatory nematodes and discusses about their possible use in the management of plant parasitic nematodes.

• Korean journal of applied entomology
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• v.27 no.1
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• pp.47-54
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• 1988

Phytophagous insects were surveyed for biological control of weeds in the southern part of korea from April 20 to July 31, 1987. Phytophagous coleopteran insects representing 12 families, 52 genera and 61 species, hemipteran insects 7 families, 18 genera and 20 species, homopteran insects 4 families, 16 genera and 21 species, hymenopteran insects 2 families, 2 genera and 3 species, and orthopteran 2 familes, 6 genera and 6 species were recorded from 58 weeds. Some chrysomelids and orthopteran insects were potential agents for biological control of weeds.

• The Plant Pathology Journal
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• v.38 no.3
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• pp.248-253
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• 2022

Erwinia amylovora is a devastating bacterial plant pathogen that infects Rosaceae including apple and pear and causes fire blight. Bacteriophages have been considered as a biological control agent for preventing bacterial infections of plants. In this study, nine bacteriophages (ΦFifi011, ΦFifi044, ΦFifi051, ΦFifi067, ΦFifi106, ΦFifi287, ΦFifi318, ΦFifi450, and ΦFifi451) were isolated from soil and water samples in seven orchards with fire blight in Korea. The genetic diversity of bacteriophage isolates was confirmed through restriction fragment length polymorphism pattern analysis. Host range of the nine phages was tested against 45 E. amylovora strains and 14 E. pyrifoliae strains and nine other bacterial strains. Among the nine phages, ΦFifi044 and ΦFifi451 infected and lysed E. amylovora only. And the remaining seven phages infected both E. amylovora and E. pyrifoliae. The results suggest that the isolated phages were different from each other and effective to control E. amylovora, providing a basis to develop biological agents and utilizing phage cocktails.

• Applied Biological Chemistry
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• v.32 no.1
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• pp.30-36
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• 1989

Some chelating agents are evaluated as an antioxidant for the autoxidation of soybean oil. Soybean oil is autoxidized under a mild condition (the flow rate of 67ml $O_{2}/min$ and $50^{\circ}C$). The antioxidant effect is measured by active oxygen method, and the spectral change of autoxidized soybean oil examined. The antioxidant effect of chelating agents is increased in order of diphenic acid, naphthoquinone, pyromellitic acid, quinolinic acid and naphthalic acid, and particularly the effect is low in diphenic acid and naphthoquinone. It is found that the effect is more clearly demonstrated by NMR rather than IR and UV and that the effect is dependent on the functional group and geometric molecular structure of chelating agents.

• Journal of Microbiology and Biotechnology
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• v.32 no.4
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• pp.504-513
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• 2022

Chitin deacetylase (CDA) inhibitors were developed as novel antifungal agents because CDA participates in critical fungal physiological and metabolic processes and increases virulence in soil-borne fungal pathogens. However, few CDA inhibitors have been reported. In this study, 150 candidate CDA inhibitors were selected from the commercial Chemdiv compound library through structure-based virtual screening. The top-ranked 25 compounds were further evaluated for biological activity. The compound J075-4187 had an IC50 of 4.24 ± 0.16 µM for AnCDA. Molecular docking calculations predicted that compound J075-4187 binds to the amino acid residues, including active sites (H101, D48). Furthermore, compound J075-4187 inhibited food spoilage fungi and plant pathogenic fungi, with minimum inhibitory concentration (MIC) at 260 ㎍/ml and minimum fungicidal concentration (MFC) at 520 ㎍/ml. Therefore, compound J075-4187 is a good candidate for use in developing antifungal agents for fungi control.

• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.1011-1021
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• 2005

Rhizobacteria are actively sought for the substitution of chemical fertilizers and pathogen control agents in environment-friendly sustainable agriculture. To be successfully commercialized in the current Korean market as agriculture biomaterials, microbial agents should exhibit both properties of plant growth promotion and pathogen control. That is, the organism must be a phytostimulator as well as a biocontrol agent. These criteria and the survival rate of a rhizobacterium, Bacillus amyloliquefaciens 7079, in the soil system were investigated to evaluate the suitability for future commercialization. B. amyloliquefaciens 7079-treated seedlings showed $22.8\%$ maximum increase in leaf-length growth, compared with water-treated controls, showing the phytostimulating property. The disease suppression rates of Phytophthora-blight of peppers and Fusarium-wilt of tomatoes by B. amyloliquefaciens 7079 were 1.5 and 2.2 times better, respectively, than by three popular chemical fungicides used in actual agricultural practices to control the respective pathogens. Survival of B. amyloliquefaciens 7079 on the rhizoplane and in the rhizosphere was favorable up to 50 days in the soil system employed. These positive properties show that B. amyloliquefaciens 7079 is likely to be a suitable candidate for commercialization to market as agricultural biomaterials.