• Journal of Microbiology and Biotechnology
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• 제10권2호
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• pp.251-257
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• 2000

Chitin synthases are identified as key enzymes of chitin biosynthesis in most of the fungi. Among them, chitin synthase II has been reported to be and essential enzyme in chitin biosynthesis, and exists as a membrane-bound form. To search and screen new antifungal agents from natural resources to inhibit chitin synthase II, the assay conditions were established using the enzyme isolated from Saccharomyces cerevisiae ECY38-38A(pAS6) that overproduces only chitin synthase II. This enzyme was activated only by partial proteolysis with trypsin. Its actibity reached the maximum at $80{\;}\mu\textrm{g}/ml$ of trypsin and was strongly stimulated by 2.0 mM $Co^{2+}$, 1.0 nM UDP-[$^{14}C$]-GicNAc, and 32 mM free-GlcNAc. Under these assay conditions, the highest chitin synthase II activity was observed by incubation at $30^{\circ}C$ for 90 min. However, and extremely narrow range of organic solvents up to as much as 25% of DMSO and 25% of MeOH was useful for determining optimal assay conditions. After a search or potent inhibitors of chitin synthase II from natural resources, prodigiosin was isolated from Serratia marcescens and purified by solvent extration and silica gel column chromatographies. The structure of prodigiosin was determined by UV, IR, Mass spectral, and NMR spectral analyses. Its molecular weight and formula were found to be 323 and $C_{20}H_{25}N_{3}O$, respectively. Prodigiosin ingibited chitin synthase II by 50% at the concentration of $115{\;}\mu\textrm{g}/ml$.

• 한국균학회지
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• 제25권4호통권83호
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• pp.354-361
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• 1997

한국산 흰주름버섯외 50종 버섯을 채집하여 석유에테르, 80%에탄올 및 멸균증류수로 각각 추출하여 153종의 추출물을 얻어 식물병원성 곰팡이에 대한 항균활성을 검색하였다. A. alternata에 항균활성은 독우산광대버섯의 물 추출물, MPC-3 버섯의 에탄올 추출물 그리고 큰낙엽버섯과 Xanthoconium affine의 석유에테르 추출물이 활성을 보였다. 잔디탄저병균, C. graminicola에 대하여는 애광대버섯, 노란길민그물버섯 그리고 흰둘레무당버섯의 석유에테르 추출물이, 해면버섯, MPC-3 버섯 그리고 주걱송편버섯의 에탄올 추출물이, 조개껍질 버섯의 물 추출물이 각각 항균활성을 보였다. 인삼뿌리썩음병균, C. destructans에 대하여는 애광대버섯, 수원그물버섯, 해면버섯, MPC-3 버섯, 주걱 송편버섯, 띠미로버섯 그리고 외대덧버섯의 에탄올 추출물이, 애광대버섯, 흰둘레무당버섯, 향버섯, 큰낙엽버섯의 석유에테르 추출물이 각각 항균활성을 보였다. 오이덩굴쪼김병균, F. o. cucumerinum에 대하여는 MPC-3 버섯의 에탄올 추출물이 항균활성을 보였다. 감자시들음병균, F. solani에 대하여는 진갈색주름버섯의 물 추출물이 그리고 무변색무당버섯의 에탄올 추출물이 각각 항균활성을 보였다. 잔디탄저병균, I. bolleyte에 대하여는 진갈색주름버섯의 물 추출물이 그리고 MPC-3버섯의 에탄올 추출물이 각각 항균활성을 보였다.

• Mycobiology
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• 제48권6호
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• pp.484-494
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• 2020

Oak wilt disease caused by Raffaelea quercus-mongolicae has emerged obviously in Korea. We selected antifungal isolates against R. quercus-mongolicae among 368 endophytic fungal isolates from different parts of oak and pine trees. The experiment was conducted in the primary and secondary screenings by dual culture test. The antifungal activity of the selected isolates was assessed in culture filtrate test based on the inhibition rates in mycelial growth, sporulation, and spore germination of oak wilt fungus. Five isolates, E089, E199, E282, E409 and E415, showed strong antifungal activity in culture filtrate test, and their antifungal activity decreased on the culture media supplemented with heated culture filtrate. Higher mycelial growth inhibitions on the unheated media were recorded in E409 (Colletotrichum acutatum), E089 (Daldinia childiae), E415 (Alternaria alternata) and E199 (Daldinia childiae) with the inhibition rates of 79.0%, 70.1%, 68.9% and 64.5%, respectively. These isolates also had the higher sporulation inhibitions on unheated media with the rates of 96.8%, 84.2%, 82.8% and 80.5%, respectively. The spore germination of the oak wilt fungus was completely inhibited by E282 (Nectria balsamea) on both unheated and heated media. These results showed that a higher number of potent antifungal isolates against oak wilt fungus was isolated from the petiole compared to the other parts. This study could contribute to the development of biological control approaches for the management of oak wilt disease caused by R. quercus-mongolicae.

• Mycobiology
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• 제40권4호
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• pp.244-251
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• 2012

In vitro and greenhouse screening of seven rhizobacterial isolates, AB05, AB10, AB11, AB12, AB14, AB15 and AB17, was conducted to investigate the plant growth promoting activities and inhibition against anthracnose caused by Colletotrichum acutatum in pepper. According to identification based on 16S rDNA sequencing, the majority of the isolates are members of Bacillus and a single isolate belongs to the genus Paenibacillus. All seven bacterial isolates were capable of inhibiting C. acutatum to various degrees. The results primarily showed that antibiotic substances produced by the selected bacteria were effective and resulted in strong antifungal activity against the fungi. However, isolate AB15 was the most effective bacterial strain, with the potential to suppress more than 50% mycelial growth of C. acutatum in vitro. Moreover, antibiotics from Paenibacillus polymyxa (AB15) and volatile compounds from Bacillus subtilis (AB14) exerted efficient antagonistic activity against the pathogens in a dual culture assay. In vivo suppression activity of selected bacteria was also analyzed in a greenhouse with the reference to their prominent in vitro antagonism efficacy. Induced systemic resistance in pepper against C. acutatum was also observed under greenhouse conditions. Where, isolate AB15 was found to be the most effective bacterial strain at suppressing pepper anthracnose under greenhouse conditions. Moreover, four isolates, AB10, AB12, AB15, and AB17, were identified as the most effective growth promoting bacteria under greenhouse conditions, with AB17 inducing the greatest enhancement of pepper growth.

• 한국환경농학회지
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• 제29권3호
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• pp.300-303
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• 2010

본 연구에서는 갈색여치의 친환경적 방제를 위해 곤충병원성 진균인 백강균(B. bassiana)의 병원력에 대한 실험을 수행하였다. 실험에 이용된 모든 균주에서 60% 이상의 병원력을 나타냈으며, 살충시간 또한 10일 이내로 짧았다. 따라서 백강균은 갈색여치의 생물학적 방제원으로 이용 가능성이 높다고 판단할 수 있다.

• 환경생물
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• 제25권3호
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• pp.267-272
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• 2007

우리나라 20개 지역의 경작토, 쓰레기 매립토, 부엽토 및 활성오니토에서 채취한 40개 토양 시료로부터 Poly(butylene succinate-co-butylene adipate) (PBSA)를 분해하는 미생물을 $37^{\circ}C$에서 강화배양과 투명환시험법을 이용하여 PBSA를 분해하는 균주를 선발하였다. 선발한 세균은 16S rDNA 염기서열분석으로 동정한 결과 Streptomyces sp. PBSA-1로 밝혀졌으며 진균은 형태적, 배양적 특징을 통하여 Aspergillus fumigatus PBSA-2와 Aspergillus fumigatus PBSA-3으로 동정되었다. 변형 Sturm test를 이용하여 선발균의 PBSA분해활성을 측정한 결과 $37^{\circ}C$에서 40일 동안 Streptomyces sp. PBSA-1은 PBSA를 83% 분해하였으며, A. fumigatus PBSA-2와 A. fumigatus PBSA-3은 PBSA를 각각 65% 및 75%분해하는 것으로 나타나 이 균주들은 PBSA의 분해에 대하여 매우 높은 활성을 가지는 것으로 평가되었다.

• The Plant Pathology Journal
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• 제31권2호
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• pp.108-114
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• 2015

Curvularia lunata is an important maize foliar fungal pathogen that distributes widely in maize growing area in China, and several key pathogenic factors have been isolated. An yeast two-hybrid (Y2H) library is a very useful platform to further unravel novel pathogenic factors in C. lunata. To construct a high-quality full length-expression cDNA library from the C. lunata for application to pathogenesis-related protein-protein interaction screening, total RNA was extracted. The SMART (Switching Mechanism At 5' end of the RNA Transcript) technique was used for cDNA synthesis. Double-stranded cDNA was ligated into the pGADT7-Rec vector with Herring Testes Carrier DNA using homologous recombination method. The ligation mixture was transformed into competent yeast AH109 cells to construct the primary cDNA library. Eventually, a high qualitative library was successfully established according to an evaluation on quality. The transformation efficiency was about $6.39{\times}10^5$ transformants/$3{\mu}g$ pGADT7-Rec. The titer of the primary cDNA library was $2.5{\times}10^8cfu/mL$. The numbers for the cDNA library was $2.46{\times}10^5$. Randomly picked clones show that the recombination rate was 88.24%. Gel electrophoresis results indicated that the fragments ranged from 0.4 kb to 3.0 kb. Melanin synthesis protein Brn1 (1,3,8-hydroxynaphthalene reductase) was used as a "bait" to test the sufficiency of the Y2H library. As a result, a cDNA clone encoding VelB protein that was known to be involved in the regulation of diverse cellular processes, including control of secondary metabolism containing melanin and toxin production in many filamentous fungi was identified. Further study on the exact role of the VelB gene is underway.

• 생명과학회지
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• 제13권5호
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• pp.604-617
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• 2003

안전성이 확보된 식용, 또는 약용식물로부터 항캔디다 활성이 우수한 항진균 후보물질을 개발하기 위해, 298종의 천연물로부터 추출부위 및 추출 용매를 달리하여 384종의 추출물을 제조하였다. 제조된 추출물의 항캔디다 활성을 disc-paper를 이용한 생육 저지환의 유무 및 크기 판정과 microbroth dilution법을 이용하여 C. albicans KCTC 1940과 S. cerevisiae IFO 0233를 대상으로 평가하였다. 그 결과 20종 식물로부터 조제된 25종의 추출물이 우수한 항캔디다 활성을 나타냄을 확인하였고, 그 중에서도 멍석딸기, 정향, 천황련, 작약, 모란, 대극잎 추출물은 강력 한 항캔디다 활성$(MIC=50 \mug/m\ell)$을 보였다. 특히, 멍석딸기(에틸아세테이트 추출물), 정향(부탄올 추출물), 호장근(에틸아세테이트 추출물), 작약(부탄올 추출물), 대극잎(메탄올 추출물)의 경우에는 C. albicans에 높은 선택독성을 나타내어, 안정성이 확보된 식물 추출물로부터 새로운 진균 감염증 치료제 개발이 가능함을 제시하였다.

• The Plant Pathology Journal
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• 제28권1호
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• pp.68-74
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• 2012

Biocontrol microbes have mainly been screened among large collections of microorganisms $via.$ nutrient-rich $in$ $vitro$ assays to identify novel and effective isolates. However, thus far, isolates from only a few genera, mainly spore-forming bacilli, have been commercially developed. In order to isolate field-effective biocontrol microbes, we screened for more than 200 oligotrophic bacterial strains, isolated from rhizospheres of various soil samples in Korea, which induced systemic resistance against the soft-rot disease caused by $Pectobacterium$ $carotovorum$ SCC1; we subsequently conducted in $planta$ bioassay screening. Two oligotrophic bacterial strains were selected for induced systemic disease resistance against the $Tobacco$ $Mosaic$ $Virus$ and the gray mold disease caused by $Botrytis$ $cinerea$. The oligotrophic bacterial strains were identified as $Pseudomonas$ $manteilii$ B001 and $Bacillus$ $cereus$ C003 by biochemical analysis and the phylogenetic analysis of the 16S rRNA sequence. These bacterial strains did not exhibit any antifungal activities against plant pathogenic fungi but evidenced several other beneficial biocontrol traits, including phosphate solubilization and gelatin utilization. Collectively, our results indicate that the isolated oligotrophic bacterial strains possessing induced systemic disease resistance could provide useful tools as effective biopesticides and might be successfully used as cost-effective and preventive biocontrol agents in the field.

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2006년도 추계 학술발표회 발표논문집
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• pp.285-289
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• 2006

In screening of algicidal bacteria, we isolated a marine bacterium which had potent algicidal effects on harmful algal bloom (HAB) species. This organism was identified as a strain very close to Bacillus subtilisby 16S rRNA gene sequencing. This bacterium, Bacillus sp. SY-1, produces very active algicidal compounds against the harmful dinoflagellate Cochlodinium polykrikoides. We isolated three algicidal compounds (MS 1056, 1070, 1084) and identified them by amino acid analyses, fast atom bombardment mass spectrometry (FAB-MS), infrared spectroscopy (IR), $^1H$, $^{13}C$, and extensive two-dimensional nuclear magnetic resonance (2D NMR) techniques including $^1H-^{15}N$ HMBC analysis. One of them, MS 1056, contains a b-amino acid residue with an alkyl side chain of $C_{15}$. MS 1056, 1070, and 1084 showed algicidal activities against C. polykrikoides with an $LC_{50}$ (6 hrs) of 2.3, 0.8, $0.6\;{\mu}g/ml$, respectively. These compounds also showed significant algicidal activities against other harmful dinoflagellates and raphidophytes. In contrast, MS 1084 showed no significant growth inhibition against various organisms coexisting with HAB species in natural environments, including bacteria, eukaryotic microalgae, and cyanobacteria, although it inhibited growth of some fungi and yeasts. These observations imply that algicidal bacterium Bacillus sp. SY-1 and its algicidal compounds could play an important role in regulating the onset and development of HABs in the natural environments.