• Mycobiology
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• 제45권4호
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• pp.370-378
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• 2017

Cylindrocarpon destructans is an ascomycete soil-borne pathogen that causes ginseng root rot. To identify effective biocontrol agents, we isolated several bacteria from ginseng cultivation soil and evaluated their antifungal activity. Among the isolated bacteria, one isolate (named JH7) was selected for its high antibiotic activity and was further examined for antagonism against fungal pathogens. Strain JH7 was identified as a Chromobacterium sp. using phylogenetic analysis based on 16S rRNA gene sequences. This strain was shown to produce antimicrobial molecules, including chitinases and proteases, but not cellulases. Additionally, the ability of JH7 to produce siderophore and solubilize insoluble phosphate supports its antagonistic and beneficial traits for plant growth. The JH7 strain suppressed the conidiation, conidial germination, and chlamydospore formation of C. destructans. Furthermore, the JH7 strain inhibited other plant pathogenic fungi. Thus, it provides a basis for developing a biocontrol agent for ginseng cultivation.

• Journal of Digestive Cancer Research
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• 제10권1호
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• pp.31-38
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• 2022

Ulcerative colitis (UC) exhibits chronic intestinal inflammatory conditions with cycles of relapse and remission. The incidence is rapidly growing in Asian countries including South Korea possibly due to changes in lifestyles. Although the etiology of inflammatory bowel disease is inconclusive, gut microbiota composition is considered a critical factor involved in the pathogenesis of UC. The overgrowth of pathogenic bacteria evokes hyper-immune responses in gut epithelium causing tissue inflammation and damage. Also, failure to regulate gut epithelium integrity due to chronic inflammation and mucus depletion accelerates bacterial translocation aggravating immune dysregulation. Gut microbiota composition responds to the diet in a very rapid manner. Epidemiological studies have indicated that the risk of UC is associated with low plant foods/high animal foods consumption. Several bacterial strains consistently found depleted in UC patients use plant food-originated dietary fiber producing short chain fatty acids to maintain epithelial integrity. These bacteria also use mucus layer mucin to keep gut microbiota diversity. These studies partly explain the association between dietary modification of gut microbiota in UC development. Further human intervention trials are required to allow the use of specific bacterial strains in the management of UC.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 1994년도 Proceedings of International Symposium on BIOLOGICAL CONTROL OF PLANT DISEASES Korean Society of Plant Pathology
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• pp.11-26
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• 1994

Crown gall of stonefruit and nut trees is one of the very few plant diseases subject to efficient biological control. The disease is caused by the soil-inhabiting bacteria Agrobacterium tumefaciens and Agrobacterium rhizogenes and the original control organism was a non-pathogenic isolate of A. rhizogenes strain K84. Control is achieved by dipping planting material in a cell suspension of strain K84 which specifically inhibits pathogenic strains containing a nopaline Ti plasmid. Because the agrocin 84-encoding plasmid (pAgK84) is conjugative, it can be transmitted from the control strain to pathogenic strains which, as a result, become immune to agrocin 84 and cannot be controlled. To prevent this happening, the transfer genes on pAgK84 were located and then largely eliminated by recombinant DNA technology. The resulting construct, strain K1026, is transfer deficient but controls crown gall just as effectively as does strain K84. Field data from Spain confirm that pAgK84 can transfer to pathogenic recipients from strain K84 but not from strain K1026. The latter has been registered in Australia as a pesticide and is the first genetically engineered organism in the world to be released fro commercial use. It is recommended as a replacement for strain K84 to prevent a breakdown in the effectiveness of biological control of crown gall. Several reports indicate that both strains K84 and K1026 sometimes control crown gall pathogens that are resistant to agrocin 84. A possible reason for this is that both strains produce a second antibiotic called 434 which inhibits growth of nearly all isolates of A. rhizogenes, both pathogens and non-pathogens. Crown gall of grapevine is caused by another species, Agrobacterium vitis. It is resistant to agrocin 84 and cannot be controlled by strains K84 or K1026. It is different from other crown gall pathogens in several characteristics, including the fact that, although a rhizosphere coloniser, its also lives systemically in the vascular tissue of grapevine. Pathogen free propagating material can be obtained from tissue culture or, less surely, by heat therapy of dormant cuttings. A number of laboratories are searching for a biocontrol strain that will prevent, or at least delay, reinfection. A non-pathogenic A. vitis strain F/25 from South Africa looks very promising in this regard.

• 농약과학회지
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• 제19권1호
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• pp.71-79
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• 2015

국내에서 서식하는 10종의 곤충에서 분리한 49균주의 장내세균으로 7종의 주요한 식물병원성 곰팡이에 대하여 항균활성을 검토하였다. 49개의 균주들은 담배장님노린재(Nesidiocoris tenuis)에서 Cedecea sp. 포함 4균주, 사슴벌레붙이(Odontotaenius disjunctus)에서 Enterobacter sp. 포함 3균주, 흰개미(Reticulitermes speratus)에서 Acinetobacter sp. 포함 4균주, 톱다리개미허리노린재(Riptortus clavatus)에서 Clavibacter sp. 포함 4균주, 열점박이잎벌레(Lema decempunctata)에서 Bacillus sp. 포함 11균주, 이십팔점박이무당벌레(Henosepilachna vigintioctopunctata)에서 Enterococcus sp. 포함 3균주, 무당벌레(Harmonia axyridis)에서 Staphylococccus sp. 포함 2균주, 콩풍뎅이(Popillia mutans)에서 Enterobacter asburiae 균을 포함한 5균주, 물땡땡이(Hydrophilus acuminatus)에서는 Aeromonas sp. 포함 7균주가 팔맥풍뎅이(Anomala octiescostata)에서는 Brucella sp. 를 포함한 7균주 등이 분리, 동정되었다. 이 49균주를 항균활성을 측정하기 위해 7종의 식물병원성 곰팡이인 토마토겹둥근무늬병(A. solani), 고추탄저병(C. gloeosporioides), 잿빛곰팡이병(B. cinerea), 시들음병(F. oxysporum), 고추역병(P. capsici), 벼문고병(R. solani), 상추균핵병(S. sclerotiorum)과 함께 PDA배지에서 대치 배양한 결과, A. solani에 대하여 항균활성을 갖는 26균주, B. cinerea에 항균활성을 갖는 6균주, C. gloeosporioides에 항균활성을 갖는 13균주, F. oxysporum에 항균활성을 갖는 11균주, P. capsici에 항균활성을 갖는 17균주, R. solani에 항균활성을 갖는 2균주와 S. sclerotiorum에 대하여 항균활성을 갖는 2균주로 나타났다. 항균활성의 결과 7종의 모든 식물병원성 곰팡이에 항균활성을 갖는 Pseudomonas aeruginosa를 선발하였다. 생물활성은 고추에 직접 분무 및 접종 처리하였을 때 고추 탄저병균(C. gloeosporioides)에 대하여 항균효과가 뚜렷하게 나타나는 것으로 확인되었다.

• Journal of Animal Science and Technology
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• 제53권6호
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• pp.549-561
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• 2011

Livestock wastewater is being discharged without treatment from Hasen's pig farm cluster in WangGoong (WG) area into the Iksan Stream, eventually flowing into the ManGyung (MG) at the upstream junction. Although it is well known that before discharge, wastewater must satisfy the pig slurry discharge standards; because of ongoing remodeling, proper treatment is not being performed. According to public records, wastewater from the WG pig farm cluster is responsible for 3.6% of MG River pollution and 2.0% of the SaeManGuem (SMG) Reservoir pollution. As a result, upstream water treatment quality has become primary concern for development of the SMG project. All physicochemical constituents and pathogenic microbes, such as chemical oxygen demand ($COD_{Cr}$), biochemical oxygen demand ($BOD_5$), total suspended solids (TSS), total nitrogen (TN), total phosphorous (TP), fecal coliforms, Escherichia coli and Salmonella at the effluent of WG Plant (S-1) exceed the effluent standards. This is mainly due to insufficient wastewater treatment: the WG Plant is under renovation to increase water purification efficiency. By comparing the water quality at the S-7 junction, where the the Iksan Stream (pig farms) and the Wanggoong Stream (no pig farms) merge, it is clear that farming facilities and improper treatment can critically affect surrounding water quality. While it is clear throughout this study that the level of all physicochemical parameters and pathogenic microbes along the Stream decreased due to sedimentation, biodegradation and/or dilution. An alarming problem was discovered: the existence of pathogenic microbe count(E coli, Salmonella) in the lagoon wastewater and the stream water. Not only were high concentrations of these pathogens themselves found, but the potential existence of more serious pathogens could rise to more dangerous conditions.

• Journal of Microbiology and Biotechnology
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• 제18권12호
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• pp.1874-1883
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• 2008

Bacterial diversity and the composition of individual communities during the composting process of swine and mushroom cultural wastes in a field-scale composter (Hazaka system) were examined using a PCR-based approach. The composting process was divided into six stages based on recorded temperature changes. Phylogenetic analysis of eighty 16S rRNA sequences from uncultured composting bacterial groups revealed the presence of representatives from three divisions, including plant pathogenic bacteria, high-molecule-degrading bacteria and spore-forming bacteria. The plant pathogen A. tumefaciens gradually decreased in abundance during the composting process and eventually disappeared during the thermophilic and cooling stage. A bacterium homologous to Bacillus humi first appeared at the early thermophilic stage and was established at the intermediate thermophilic, post-thermophilic, and cooling stages. It was not possible to isolate the B. humi during any of the stages using general culture techniques.

• 한국균학회지
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• 제24권1호통권76호
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• pp.17-24
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• 1996

목재부후성 담자균류의 배양 균사체의 생물활성을 조사하기 위하여 항균활성, 식물생장조절활성, 항암활성 및 그들이 생산하는 효소활성을 검정한 결과 Coriozus versicolor 5129와 C. pubescens 5131 균주는 그람양성세균에, Lenzites betulina 8029 균주는 그람음성세균에 저지 효과를 나타내었으며 L. betulina 8085 균주는 세균과 진균에 저지 효과를 나타내어 광범위한 항균 spectrum을 보였다. 대부분의 균주가 0.8ml/ml 농도 처리시 배추 및 무의 발아 및 생장을 억제하였으며, 특히 Fomitopsis pinicolor 8059와 Fomitella fraxinea 8084 균주의 경우 생육을 장하게 억제하였다. 그러나, Bjerkandera adusta 8054 균주는 0.4 및 0.2ml/ml농도에서 배추 및 무의 생육을 촉진하였다. 몇종의 목재부후균 다당체를 추출하여 암세포를 이식한 ICR mouse에 투여한 결과 거의 전 균주가 항종양 작용을 나타내었으나 버섯종류 간에 큰 차이를 보였고 그중 L. betulina 8029와 미분류된 8058 균주는 효과가 비교적 높았다. 목재부후균의 세룰로스와 리그닌 분해력은 거의 전 공시균주에서 나타났고 종류간에 역가가 다양하여 강력한 분해균의 선발 가능성을 보였다.

• 한국환경과학회지
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• 제29권5호
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• pp.435-443
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• 2020

The purpose of this study was to investigate eco-friendly measures to manage major diseases which cause heavy economic damages to ginseng. Morphological, physicochemical, and molecular biological species identification was carried out after isolating useful antagonistic bacteria from ginseng fields. In addition, optimal conditions for mass culture were established, and he efficacy of the bacteria in the prevention of the diseases was verified in the field. The results showed that about 150 bacteria were extracted from 150 ginseng fields in the whole county. Among them, B. pyrrocinia LA101 was finally selected, which had a strong antagonistic potency against Alternaria panax, Botrytis cinerea, Rhizoctonia solani, and Cylindrocarpon destructans on agar media. The B. pyrrocinia LA101 is a baculiform gram-negative bacterium identified as Burkholderia pyrrocinia according to results from an API(Analytical Profile Index) kit, 16S rRNA, and gyrase gene sequencing analysis. It was donated to the microbe bank of the Agricultural Genetic Resources Center at the National Academy of Agriculture Science under the Rural Development Administration on September 28, 2011 (Donation No. KACC91663P). A patent for the mass culture technology was granted in August 2012 (Patent No. 10-1175532).

• 한국환경농학회지
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• 제30권3호
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• pp.346-356
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• 2011

BACKGROUND: Chemical fungicides not only may pollute the ecosystem but also can be environmentally hazardous, as the chemicals accumulate in soil. Biological control is a frequently-used environment-friendly alternative to chemical pesticides in phytopathogen management. However, the use of microbial products as fungicides has limitations. This study isolated and characterized a three-antifungal-enzyme (chitinase, cellulase, and ${\beta}$-1,3-glucanase)-producing bacterium, and examined the conditions required to optimize the production of the antifungal enzymes. METHOD AND RESULTS: The antifungal enzymes chitinase, cellulase, and ${\beta}$-1,3-glucanase were produced by bacteria isolated from an sawmill in Korea. Based on the 16S ribosomal DNA sequence analysis, the bacterial strain AM50 was identical to Streptomyces sp. And their antifungal activity was optimized when Streptomyces sp. AM50 was grown aerobically in a medium composed of 0.4% chitin, 0.4% starch, 0.2% ammonium sulfate, 0.11% $Na_2HPO_4$, 0.07% $KH_2PO_4$, 0.0001% $MgSO_4$, and 0.0001% $MnSO_4$ at $30^{\circ}C$. A culture broth of Streptomyces sp. AM50 showed antifungal activity towards the hyphae of plant pathogenic fungi, including hyphae swelling and lysis in P. capsici, factors that may contribute to its suppression of plant pathogenic fungi. CONCLUSION(S): This study demonstrated the multiantifungal enzyme production by Streptomyces sp. AM50 for the biological control of major plant pathogens. Further studies will investigate the synergistic effect, to the growth regulations by biogenic amines and antifungal enzyme gene promoter.

• The Plant Pathology Journal
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• 제39권4호
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• pp.409-416
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• 2023

Bacterial leaf blight of carrots caused by Xanthomonas hortorum pv. carotae (Xhc) is an important worldwide seed-borne disease. In 2012 and 2013, symptoms similar to bacterial leaf blight were found in carrot farms in Jeju Island, Korea. The phenotypic characteristics of the Korean isolation strains were similar to the type strain of Xhc. Pathogenicity showed symptoms on the 14th day after inoculation on carrot plants. Identification by genetic method was multi-position sequencing of the isolated strain JJ2001 was performed using four genes (danK, gyrB, fyuA, and rpoD). The isolated strain was confirmed to be most similar to Xhc M081. Furthermore, in order to analyze the genetic characteristics of the isolated strain, whole genome analysis was performed through the next-generation sequencing method. The draft genome size of JJ2001 is 5,443,372 bp, which contains 63.57% of G + C and has 4,547 open reading frames. Specifically, the classification of pathovar can be confirmed to be similar to that of the host lineage. Plant pathogenic factors and determinants of the majority of the secretion system are conserved in strain JJ2001. This genetic information enables detailed comparative analysis in the pathovar stage of pathogenic bacteria. Furthermore, these findings provide basic data for the distribution and diagnosis of Xanthomonas hortorum pv. carotae, a major plant pathogen that infects carrots in Korea.