• 한국미생물·생명공학회지
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• 제31권1호
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• pp.18-24
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• 2003

벼과식물과 관련된 질소고정균을 분리하기 위하여 한반도 남부지방의 19지역에서 쌀, 밀, 귀리, 보리, 호밀, 옥수수 등을 채집하여 이들의 뿌리로부터 free living bacteria와 endophyte를 분류하였다. Colony의 형태, 크기, 색깔 등과 16S rDNA 염기서열을 근거로 63종으로 분류하였다. nifH 유전자 염기서열 결정과 nitrogenase 활성 측정을 통하여 분리균주 모두 질소고정 능력이 있음을 확인하였다. 그리고 식물에서 분리한 내생균의 특징 중 하나인 cellulase활성이 대부분의 분리 균주에서 확인되었다.

• 식물병연구
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• 제18권3호
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• pp.210-216
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• 2012

Plasmodiophora brassicae에 의한 배추 뿌리혹병은 배추뿐만 아니라 순무, 양배추에 발병하여 큰 피해를 주는 병원균이다. 배추 뿌리혹병균에 길항효과가 있는 미생물을 선발하기 위하여 배추 조직에서 분리한 Flavobacterium hercynium EPB-C313 균주의 항균활성 검정을 하였고, 포장시험을 통하여 배추 뿌리혹병에 대한 방제효과를 조사하였다. F. hercynium EPB-C313의 균체, 배양액, 배양여액를 배추 뿌리혹병 휴면포자와 혼합 처리하여 24시간 후 조사하였을 때 각각 90.4%, 36.8% 및 26.0%의 휴면포자가 불활성화 되었다. 온실 포트검정에서는 배추의 어린묘를 F. hercynium EPB-C313 배양액에 침지한 후 정식하면 뿌리혹 형성 억제율이 100%로 대조약제 fluazinam액상수 화제의 91.7%보다 우수한 효과를 나타내었다. 배추 뿌리혹병이 50% 이상 발병되었던 재배포장에 F. hercynium EPB-C313 혼합펠렛을 토양혼화 하고, F. hercynium EPBC313 배양액의 유묘관주 및 정식 10일 후 1회 토양관주하면 63.7%의 방제효과를 보였다. 이상의 결과로 볼 때 F. hercynium EPB-C313 균주는 매우 유용한 배추 뿌리혹병 생물적 방제제로 판단된다.

• 미생물학회지
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• 제43권4호
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• pp.341-345
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• 2007

식용 및 약용으로 광범위하게 이용되고 있는 갈근 내부조직으로부터 강한 점액성 물질을 생산하는 50개의 내생 균주를 분리하였다. 다당류의 수율이 높은 내생균주 HDN-14, TDG-3및 TNB-3 균주를 선발하여 이들이 생산하는 다당류의 구성당 조성을 분석한 결과 glucose ($45.6{\sim}63.1%$), maltose ($14.6{\sim}23.7%$) 및 fructose ($17.4{\sim}23.7%$)가 검출되었다. 이들 분리균주의 16S rDNA 염기서열(약 1,300bp)을 결정하여 계통학적 위치를 검토한 결좌, ${\grmma}$-Proteobacteria 그룹의 Pseudomonas 속에 속하는 균주임이 확인되었으며, HDN-14과 TNB-3 균주는 Pseudomonas $koreensis^T$, Pseudomonas $jessenii^T$와 $99.06{\sim}99.32%$의 상동성을 나타내었으며 TDG-3 균주는 Pseudomonas $plecoglossicida^T$, Pseudomonas $mosselii^T$, Pseudomonas $monteilii^T$와 $99.48{\sim}99.74%$ 상동성을 나타내었다. 이들 분리균주는 주요 균체지방산으로 $3OH-C_{10:0}$, $2OH-C_{12:0}$, $3OH-C_{12:0}$, $3OH-C_{12:0}$ 및 $3OH-C_{12:1}$가 검출되었으며, TDG-3 균주의 경우, 3-OH $C_{13:0}$, 3-OH $C_{14:0}$, 3-OH $C_{15:0}$ 및 3-OH $C_{16:0}$등 다양한 종류의 3-OH 지방산이 검출되어 기존의 Pseudomonas 종과 비교하여 매우 특징적인 성질을 나타내었다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.161-161
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• 2017

Seed endophytes are very remarkable groups of bacteria for their unique abilities of being vertically transmitted and conserved. As plants attain hybrid vigor and heterosis in the process of crossbreeding, this might also lead to the changes in the community structure and diversity of plant endophytes in the hybrid plants ultimately affecting the endophytes of the seeds. It would be interesting to characterize how seed endophyte composition change over time. The objective of this study is to gain insights into the influence of natural crossbreeding and parental lineage in the seed bacterial endophytic communities of two pure inbred lines exploring contributions of the two most important sources of plant endophytes - colonization from external sources and vertical transmission via seeds. Total genomic DNA was isolated from rice seeds and bacterial DNA was selectively amplified by PCR. The diversity of endophytic bacteria was studied through Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis. Diversity between the original parents and the pure inbred line may show significant differences in terms of richness, evenness and diversity indices. Heat maps reveal astonishing contributions of both or either parents (IR29 ${\times}$ Pokkali and AT401 ${\times}$ IR31868) in the shaping of the bacterial seed endophytes of the hybrid, FL478 and IC32, respectively. Most of the T-RFs of the subsequent pure inbred line could be traced to any or both of the parents. Comparison of common and genotype-specific T-RFs of parents and their offspring reveals that majority of the T-RFs are shared suggesting higher transmission of bacterial communities common to both parents. The parents influence the bacterial community of their offspring. Unique T-RFs of the offspring also suggest external sources of colonization particularly as the seeds are cultivated in different ecogeographical locations. This study showed that host parental lines contributed greatly in the shaping of bacterial seed endophytes of their offspring. It also revealed transmission and potential conservation of core seed bacterial endophytes that generally become the dominant microbiota in the succeeding generations of plant hosts.

• 한국약용작물학회:학술대회논문집
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• 한국약용작물학회 2011년도 추계학술발표회
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• pp.372-373
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• 2011

• Journal of Microbiology and Biotechnology
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• 제22권3호
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• pp.407-415
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• 2012

An endophytic bacterium, Bacillus thuringiensis GS1, was isolated from bracken (Pteridium aquilinum) and found to have maximal production of chitinase (4.3 units/ml) at 5 days after culture. This study investigated the ability of B. thuringiensis GS1 to induce resistance to Rhizoctonia solani KACC 40111 (RS) in cucumber plants. Chitinase activity was greatest in RS-treated plants at 4 days. ${\beta}$-1,3-Glucanase activity was highest in GS1-treated plants at 5 days. Guaiacol peroxidase (GPOD) activity increased continuously in all treated plants for 5 days. Ascorbate peroxidase (APX) activity in RS-treated plants was increased 1.5-fold compared with the control at 4 days. Polyphenol oxidase (PPO) activity in RS-treated plants was increased 1.5-fold compared with the control at 3 days. At 5 days after treatment, activity staining revealed three bands with chitinase activity (Ch1, Ch2, and Ch3) on SDS-PAGE of cucumber plants treated with GS1+RS, whereas only one band was observed for RS-treated plants (Ch2). One GPOD isozyme (Gp1) was also observed in response to treatment with RS and GS1+RS at 4 days. One APX band (Ap2) was present on the native-PAGE gel of the control, and GS1- and GS1+RS-treated plants at 1 day. PPO bands (Po1 and Po2) from RS- and GS1+RS-treated plants were stronger than in the control and GS1-treated plants upon native-PAGE at 5 days. Taken together, these results indicate that the induction of PR proteins and defense-related enzymes by B. thuringiensis GS1 might have suppressed the damping-off caused by R. solani KACC 40111 in cucumber plants.

• Journal of Microbiology and Biotechnology
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• 제33권6호
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• pp.806-822
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• 2023

In the current study we assessed a new crystallized compound, 5-(1-hydroxybutyl)-4-methoxy-3-methyl-2H-pyran-2-one (C-HMMP), from the endophytic fungus Colletotrichum acutatum residing in the medicinal plant Angelica sinensis for its in vitro antimicrobial, antibiofilm, antioxidant, antimalarial, and anti-proliferative properties. The promising compound was identified as C-HMMP through antimicrobial-guided fraction. The structure of C-HMMP was unambiguously confirmed by 2D NMR and HIRS spectroscopic analysis. Antimicrobial property testing of C-HMMP showed it to be effective against a variety of pathogenic bacteria and fungi with MICs ranging from 3.9 to 31.25 ㎍/ml. The compound displayed excellent antibiofilm activity against C. albicans, S. aureus, and K. pneumonia. Furthermore, the antimalarial and radical scavenging activities of C-HMMP were clearly dosedependent, with IC50 values of 0.15 and 131.2 ㎍/ml. The anti-proliferative activity of C-HMMP against the HepG-2, HeLa, and MCF-7 cell lines in vitro was investigated by MTT assay, revealing notable anti-proliferative activity with IC50 values of 114.1, 90, and 133.6 ㎍/ml, respectively. Moreover, CHMMP successfully targets topoisomerase I and demonstrated beneficial anti-mutagenicity in the Ames test against the reactive carcinogenic mutagen, 2-aminofluorene (2-AF). Finally, the compound inhibited the activity of α-glucosidase and α-amylase with IC50 values of 144.7 and 118.6 ㎍/ml, respectively. To the best of our knowledge, the identified compound C-HMMP was obtained for the first time from C. acutatum of A. sinensis, and this study demonstrated that C-HMMP has relevant biological significance and could provide better therapeutic targets against disease.

• Advances in nano research
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• 제13권4호
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• pp.325-339
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• 2022

Endophytes ascertain a symbiotic relationship with plants as promoters of growth, defense mechanism etc. This study is a first report to screen the endophytic population in Waltheria indica, a tropical medicinal plant. 5 bacterial and 3 fungal strains in leaves, 3 bacterial and 1 yeast species in stems were differentiated morphologically and identified by biochemical and molecular methods. The phylogenetic tree of the isolated endophytes was constructed using MEGA X. Silver nanoparticles were biosynthesized from a rare endophytic bacterium Cupriavidus metallidurans isolated from the leaf of W. indica. The formation of silver nanoparticles was confirmed by UV-Visible spectrophotometer that evidenced a strong absorption band at 408.5 nm of UV-Visible range with crystalline nature and average particle size of 16.4 nm by Particle size analyzer. The Fourier Transform Infra-Red spectrum displayed the presence of various functional groups that stabilized the nanoparticles. X-ray diffraction peaks were conferred to face centered cubic structure. Transmission Electron Microscope and Scanning Electron Microscope revealed the spherical-shaped, polycrystalline nature with the presence of elemental silver analyzed by Energy Dispersive of X-Ray spectrum. Selected area electron diffraction also confirmed the orientation of AgNPs at 111, 200, 220, 311 planes similar to X-ray diffraction analysis. The synthesized nanoparticles are evaluated for antimicrobial activity against 7 bacterial and 3 fungal pathogens. A good zone of inhibition was observed against pathogenic bacteria than fungal pathogens. Thus the study could hold a key aspect in drug discovery research and other pharmacological conducts of human clinical conditions.

• Journal of Microbiology and Biotechnology
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• 제22권12호
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• pp.1597-1604
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• 2012

Genus Bacillus is a spore-forming bacterium that has unique properties in cell differentiation, allowing the forming of spores in stress conditions and activated in the vegetative cell, with suitable environments occurring during the life cycle acting as a trigger. Their habitat is mainly in soil; thus, many species of Bacillus are associated with plants as well as rhizosphere bacteria and endophytic bacteria. Signal transduction is the principal mechanism of interactions, both within the cell community and with the external environment, which provides the subsequent functions or properties for the cell. The antimicrobial compounds of Bacillus sp. are potentially useful products, which have been used in agriculture for the inhibition of phytopathogens, for the stimulation of plant growth, and in the food industry as probiotics. There are two systems for the synthesis of these substances: nonribosomal synthesis of cyclic lipopeptides (NRPS) and polyketides (PKS). For each group, the structures, properties, and genes of the main products are described. The different compounds described and the way in which they co-exist exhibit the relationship of Bacillus substances to plants, humans, and animals.

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
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• pp.95.2-96
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• 2003

In order to develop a new microbial fungicide for the control of vegetable diseases using endophytic bacteria, a total of 260 bacterial strains were isolated from fresh tissues of 5 plant species. After they were cultured in broth media, their antifungal activities were screened by in vivo bioassays against Botrytis cinerea(tomato gray mold), Pythium ultimum(cucumber damping-off), Phytopkhora infestans(tomato late blight), Colletotrichum orbiculare(cucumber anthracnose), and Blumeria graminis f. sp. hordei(barley powdery mildew). As the results of screening, 38 bacterial strains showed potent antifungal activities against at least one of 5 plant pathogens. A bacterial strain EB072 displayed potent disease control activities against 3 plant diseases. Among the bacterial strains with a potent antifungal activity against cucunlber anthracnose, three bacterial strains, EB054, EB151 and EB215, also displayed a potent in vitro antifungal activity against C. acutatum, a fungal agent causing pepper anthracnose. A bacterial strain EB215 obtained from roots of cucumber was identified as Burkholderia cepacia based on its physiological and biochemical characteristics and 165 rRNA gene sequence. An antifungal substance was isolated from the liquid cultures of B. cepacia EB215 strain by ethyl acetate partitioning, repeated silica gel column chromatography, and invitro bioassay, Its structural determination is in progress by various instrumental analyses.