• 한국균학회지
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• 제42권4호
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• pp.333-340
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• 2014

미생물을 이용한 생물학적 방제제의 개발을 위해 연작피해가 없는 순창군 토양으로부터 다양한 미생물 201종을 분리하였고, 이들의 생물학적 활성을 조사하였다. 201종의 분리 세균 중에서 다양한 식물병원성 곰팡이에 대하여 항균활성이 우수한 5종을 선별하였다. 5종의 분리주에 대하여 siderophore를 생산하며 cellulase, protease, amylase와 같은 곰팡이 세포벽 분해효소를 생산하는 능력이 가장 우수한 SCS3 균주를 최종 선별하였다. 최종 선별한 균주 SCS3의 형태학적, 생리학적 및 생화학적 특성을 조사하였고, 16S rRNA 염기서열의 분석에 의해 B. subtilis SCS3으로 명명하였으며, 염기서열 분석에 기반하여 계통수를 작성하였다. 이상의 결과로부터 B. subtilis SCS3은 식물병원성 곰팡이의 방제를 위한 생물학적 방제제로 유용하게 이용될 수 있을 것으로 생각한다.

• The Plant Pathology Journal
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• 제36권3호
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• pp.244-254
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• 2020

Gom-chwi (Ligularia fischeri) is severely infected with Phytophthora drechsleri, the causal organism of Phytophthora root rot, an economically important crop disease that needs management throughout the cultivation period. In the present study, Phytophthora root rot was controlled by using bacterial isolates from rhizosphere soils collected from various plants and screened for antagonistic activity against P. drechsleri. A total of 172 bacterial strains were isolated, of which, 49 strains showed antagonistic activities by dual culture assay. In the seedling assay, six out of the 49 strains showed a predominant effect on suppressing P. drechsleri. Among the six strains, the ObRS-5 strain showed remarkable against P. drechsleri when treated with seed dipping or soil drenching. The ObRS-5 strain was identified as Enterobacter asburiae based on 16S ribosomal RNA gene sequences analysis. The bacterial cells of E. asburiae ObRS-5 significantly suppressed sporangium formation and zoospore germination in P. drechsleri by 87.4% and 66.7%, respectively. In addition, culture filtrate of E. asburiae ObRS-5 also significantly inhibited sporangium formation and zoospore germination by 97.0% and 67.6%, respectively. Soil drenched bacterial cells, filtrate, and culture solution of E. asburiae ObRS-5 effectively suppressed Phytophthora root rot by 63.2%, 57.9%, and 81.1%, respectively. Thus, E. asburiae ObRS-5 could be used as a potential agent for the biological control of Phytophthora root rot infecting gom-chwi.

• Preventive Nutrition and Food Science
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• 제2권2호
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• pp.109-120
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• 1997

In order to elucidate roles of lactic acid bacteria(LAB) for the antibiosis occurring in th fermenting environment of Kimchi, 2.052 strains of LAB were isolated from Kimchi. Fifty tow strains which showed antagonistic effect against 4 indicator strains were finally selected and investigated. Based upon responses to protease treatment, antibiosis of the 52 strains of LAB were classified into 3 types. Type A antibiosis resulted from action of antibiotic-like substances which were not affected by protease treatment and which had broad action spectra against even natural inhabitants of Kimchi. Type B antibiosis was due to bacteriocin-like substances which were very sensitive to treatment of protease and more effective against foreign bacteria than original inhabitant microflora. Type C antibiosis was owing to proteinaceous compounds which were activated or induced by the presence of protease and then exerted antibacterial activities. Therefore, lactic acid bacteria appeared to contribute to antibiosis of Kimchi by the concerted action of these three different types of antibacterial compounds. As one of model system for type B bacteriocin, the antagonistic compound produced by LAB31-9 as well as th producer strain itself was further charaacterized. Strain LAB31-9 was identified as L. casei. Bacteriocin produced by LAB31-9 was proteinaceous and stable over wide range of pH and to various solvents, but very labile to heat treatment. Its mode of action was bactericidal. Based upon these data, bacteriocin produced by LAB31-9 was named as 'caseicin K319'. Genetic determinant for the bacteriocin production of LAB31-9 was located in the chromosome.

• Journal of Microbiology and Biotechnology
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• 제13권3호
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• pp.415-421
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• 2003

A bacterium, Pseudomonas fluorescens 2112, that is antagonistic against a red-pepper blight-causing fungus, Phytophthora capsici, was isolated from the local soil of Gyongju, Korea. This strain formed an orange-colored clear halo zone on chrome azurol S (CAS) blue agar, suggesting the production of a siderophore in addition to an antifungal antibiotic. The optimal culture conditions for siderophore production by P. fluorescens 2112 were 30-h cultivation at $25^{\circ}C$ and pH 6.5 in King's B medium. The presence of $20{\mu}g/ml\;of\;Fe^3+$ ion or EDDHA promoted the production of siderophore in King's B medium. The siderophore was purified from culture broth by CM-Sephadex C-25 and Sephadex G-25 column chromatographies. The UV spectra of the purified siderophore was the same as that of pyoverdins or pseudobactins. The molecular mass was 1,958 Da determined by FAB-rlass spectrometer, and the amino acid composition analysis showed that the purified siderophore consisted of glycine/threonine/serine/glutamic acid/alanine/lysine with the molar ratio of 3:2:1:1:1:1, DL-Threo-${\beta}$-hydroxyaspartic acid and $N^{\delta}$-hydroxyornithine, two of the essential constituents of pyoverdin, were also found. The purified siderophore pyoverdin showed strong in vitro and in vivo antagonistic activities against phytophthora blight-causing P. capsici. Especially in an in vivo pot test, the siderophore protected red-pepper Capsicum annum L. very well from the attack of P. capsici. These results indicated that the purified siderophore of P. fluorescens 2112 played a critical role in the biocontrol of the red-pepper blight disease, equivalent to treatment by P.fluorescens 2112 cells.

• 생명과학회지
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• 제12권2호
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• pp.200-207
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• 2002

채소류 모잘록병균인 Pythium ultimun에 길항하는 미생물을 분리하기 위해 체소류 뿌리를 균원시료로 하여 약600여종의 근권미생물을 분리하였고, 그중 5종의 근권미생물이 길항력을 나타내어 가장 높은 길항력 높은 Yl-37 균주를 최종 선별하였다. 분리한 길항균 YJ-37을 Bergey's Mannual of Systematic Bacteriology의 방법에 준하여 미생물의 형태학적, 배양학적, 생리·생화학적 특성을 조사 하였으며, 미생물의 세포벽의 지방산의 조성으로 자동 동정하는 Sherlock system을 이용하는 방법과 16S rDNA의 부분염기서열을 결정하여 동정하는 방법 등 3가지 방법으로 조사한 결과, 근권 길항미생물인 YJ-37 균주는 Bacillus ehimensis로 동정되었다. 채소류 모잘록병균 Pythium ultimun과 Rhizoctonia solani AG-4 이외에도 B. ehimensis YJ-37에 의한 병원성 진균의 길항력을 조사한 결과, Alternaria altrata, Collectotrichum gloeosporioides, Didymella bryoniae, Fu-sarium moniliforme, F oxysporum, F. oxysporum cucumerinum, F. oxysporum niveum, Gloeosporium sp., Glomerella sp., G. cingulata, G. lagenaria, Penicillium digitatum, P. itazicum, Phytophthora capsici, Sclerotinia sclerotiorum, Stemprhyzium solani등 대부분의 병원균에 대해서 항진균 활성을 나타내었다.

• Applied Biological Chemistry
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• 제47권2호
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• pp.164-169
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• 2004

감자더뎅이병 방제용 생물제제(biocontrol agenL BCA)를 개발하기 위하여 국내 토양으로부터 분리된 5,000여 방선균 균주를 대상으로 더뎅이병 관련 병원균(Streptomyces scabiei및 S. turgidiscabies)에 대한 in vitro또는 in vivo 활성검정을 실시하였다. 활성검정 결과 길항력이 우수한 균주로서 9균주가 선발되었으며 실제 재배포장에서 사용되고 있는 dazomet및 mancozeb 등 농약에 대한 감수성 시험을 실시하여 A020645 균주가 길항활성 뿐만 아니라 약제저항성이 가장 높음을 확인하고 더뎅이병 방제용 BCA 균주로 선발하였다. 본 균주로부터 항균활성물질을 분리하기 위하여 액체배양액으로부터 음이온교환 크로마토그래피(anion exchange chromatography), solidphase(ODS) extraction, TLC, 역상 HPLC 등을 실시하여 최종적으로 compound A와 B를 순수 분리하였다. Compound A와 B는 NMR 분석 결과 nucleoside계 화합물로 판단된다.

• 식물병연구
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• 제28권3호
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• pp.152-161
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• 2022

Several types of chemical bactericides have been used to control fire blight. However, their excessive usage leads to environmental deterioration. Therefore, several researchers have analyzed antagonistic microorganisms as promising, effective, and safe biological control agents (BCAs). The primary aim of this study was to screen for potential antagonistic bacteria that suppress Erwinia amylovora. Among the 45 isolates studied, 5 strains showed the largest inhibition zone against E. amylovora. 16S rRNA gene sequencing identified them as Bacillus amyloliquefaciens (KPB 15), B. stratosphericus (KPB 21), B. altitudinis (KPB 25), B. safensis (KPB 31), and B. subtilis (KPB 39). KPB 25 and 31 reduced the lesion size of fire blight by 50% in immature apple fruits, and did not show antagonism against each other. Therefore, KPB 25 and 31 were selected to develop an antagonistic mixture against fire blight. Although the mixture with KPB 25 and 31 showed a slightly increased ability to reduce lesion size on immature fruits, they did not exhibit a synergistic effect in reducing E. amylovora population compared to each strain alone. Nevertheless, we have identified these two strains as useful and novel BCAs against fire blight with additional benefits safety and potential in developing a mixture without loss of their activity, owing to the absence of antagonism against each other.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.103.1-103
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• 2003

An antagonistic bacteria, Stenotrophomonas maitophilia BW-13 strain which was effectively inhibited mycerial growth of Bottom rot pathogen, Rhizoctonia solani PY-1 strain was isolated from the rhizosphere of the lettuce in Uiryeong-Gun, Gyeongsangnam-Do from 2002 to 2003. For the biological control, the most suitable inoculum and its density of pathogen, PY-1 strain ware tested prior biological control test, For the pathogenicity test, A inoculum (wheat bran)sawdust+rice bran+PDB) showing disease incidence of 100％ was selected as the most suitable inoculum, which showed more effective than B inoculum (sawdust＋rice bran＋DW) and mycelial disc. also, In selection of the amount of inoculum (40g, 50g, 60g, 70g, 80g), most suitable amount of inoculum of pathogen determined as 40g showing disease incidence of 80％. For the selection of effective microorganism to control bottom rot on lettuce, about 200 isolates were isolated from the diseased soil and lettuce leaves, and examined their antifungal activity to the pathogen on PDA. As the pots assay, BW-13 strain showed the highest control value as 90％, and followed by R-13 and R-26 strain as 80％ and 60％, respectively. Selected BW-13 isolates identified as 5. maltophilia (GeneBank accession no. AJ293473.1, 99％) by 16S rRNA sequencing. This is the first report on the biological control using by S. maltophilia to the bottom rot pathogen, Rhizoctonia solani PY-1 strain.

• Journal of Microbiology and Biotechnology
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• 제20권2호
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• pp.281-286
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• 2010

A Pseudomonas fluorescens strain was isolated and found to show antagonistic activity against phytopathogenic fungi and to possess a gene responsible for production of antibiotic 2,4-diacetylphloroglucinol. For the extension of biocontrol range, a gene for an Androetonus australis Hector insect toxin 1 (AaHIT1), one of the most known toxic insect-selective peptides, was designed and synthesized according to the preferred codon usage of Pseudomonas fluorescens, cloned, and transformed into the strain by pSUP106 vector, a broad-host-range plasmid. Bioassays indicated that the engineered strain was able to produce AaHIT1 with insecticidal activity, and at the same time retain the activity against plant pathogen. The experiments for nonplanted soil and rhizosphere colonization showed that, similar to the population of the wild-type strain, that of the engineered strain remained relatively constant in the first 10 days, and the subsequent 50 days, suggesting that AaHIT1 expression in the bacterial cell does not substantially impair its long-term colonization. It is first reported that a Pseudomonas fluorescens strain expressing an active scorpion neurotoxin has dual activity against phytopathogenic fungi and insects, making at attractive for agronomic applications.

• 식물병연구
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• 제10권1호
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• pp.63-68
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• 2004

벼에서 문제시되는 도열병과 잎집무의마름병을 생물학적으로 방제하기 위해 병원균과 생태학적 지위가 비슷한 벼 뿌리에서 내생하는 S. marcescens 23 균주를 분리하였다. 선발 균주들을 공시하여 R. solani와 P. grisea에 대한 길항능력을 검정하여 R. solani와 P. grisea에 각각 83.9％. 88.3％의 높은 억제율을 보인 RSm220 균주를 선발하였다. 선발된 RSm220은 생리ㆍ생화학적 특성 검정결과 S. marcescens type strain과 높은 상관성을 나타내었고. 16S rDNA sequencing에 의한 계통 분석에 의해 S. marcescens의 16S rDNA sequence에 98.2％ 유사성을 나타내어 S. marcescens로 동정되었다 내생성 S. marcescens RSm220은 벼 도열병과 잎집무늬마름병에 대한 생물학적 방제제로의 사용이 가능할 것으로 사료된다.