• Journal of Microbiology and Biotechnology
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• 제18권9호
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• pp.1578-1583
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• 2008

Rhizobacteria are used as inoculants to enhance crop yield and for biological control of fungal pathogens. Fluorescent pseudomonads isolated from the rhizosphere of groundnut showed suppression of the phytopathogen Macrophomina phaseolina that causes charcoal rot of groundnut, an economically important agroproduct. Two strains of fluorescent pseudomonads, designated as PS1 and PS2, were selected as a result of in vitro antifungal activity. After 5 days of incubation at $28{\pm}1^{\circ}C$, both PS1 and PS2 caused clear inhibition zones in dual cultures, restricting the growth of M. phaseolina by 71 % and 74%, respectively. Both the strains were capable of producing siderophores, indole acetic acid, and hydrocyanic acid, and causing phosphate solubilization under normal growth conditions. These strains, when used as inoculants in groundnut, enhanced germination up to 15% and 30% with subsequent increase in grain yield by 66% and 77%, respectively. Conversely, when the pathogen alone was tested 57% decrease in yield was recorded. Thus the studies revealed the potential of the two pseudomonads not only as biocontrol agents against M. phaseolina, but also as a good growth promoter for groundnut.

• Journal of Microbiology and Biotechnology
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• 제22권1호
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• pp.13-24
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• 2012

The genetic diversity of plant growth-promoting rhizobacterial (PGPR) fluorescent pseudomonads associated with the sugarcane (Saccharum officinarum L.) rhizosphere was analyzed. Selected isolates were screened for plant growthpromoting properties including production of indole acetic acid, phosphate solubilization, denitrification ability, and production of antifungal metabolites. Furthermore, 16S rDNA sequence analysis was performed to identify and differentiate these isolates. Based on 16S rDNA sequence similarity, the isolates were designated as Pseudomonas plecoglossicida, P. fluorescens, P. libaniensis, and P. aeruginosa. Differentiation of isolates belonging to the same group was achieved through different genomic DNA fingerprinting techniques, including randomly amplified polymorphic DNA (RAPD), amplified ribosomal DNA restriction analysis (ARDRA), repetitive extragenic palindromic (REP), enterobacterial repetitive intergenic consensus (ERIC), and bacterial repetitive BOX elements (BOX) analyses. The genetic diversity observed among the isolates and rep-PCR-generated fingerprinting patterns revealed that PGPR fluorescent pseudomonads are associated with the rhizosphere of sugarcane and that P. plecoglossicida is a dominant species. The knowledge obtained herein regarding the genetic and functional diversity of fluorescent pseudomonads associated with the sugarcane rhizosphere is useful for understanding their ecological role and potential utilization in sustainable agriculture.

• Journal of Microbiology and Biotechnology
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• 제17권6호
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• pp.919-927
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• 2007

Antagonistic fluorescent pseudomonads isolated from rhizospheric soil of rice were characterized by 16S rRNA amplicon and fatty acid methyl ester (FAME) analyses. Antagonistic isolates were grown in the fermentation media, and production of antibiotics was confirmed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Production of fungal cell-wall-degrading enzymes such as protease, cellulase, pectinase, and chitinase was determined. Dendrogram based on the major and differentiating fatty acids resulted into 5 clusters, viz., cluster I (P. pseudoalcaligenes group), cluster II (P. plecoglossicida group), cluster III (P. fluorescens group), cluster IV (P. aeruginosa group), and cluster V (P. putida group). Characteristic presence of high relative proportions of cyclopropane (17:0 CYCLO w7c) was observed in antagonistic bacteria. Data revealed biodiversity among antagonistic fluorescent pseudomonads associated with the rice rhizosphere. Results presented in this study will help to identify the antagonistic isolates and to determine their mechanisms that mediate antagonism against fungal pathogens of rice.

• 한국균학회지
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• 제8권1호
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• pp.59-62
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• 1980

Investigation on modification of aflatoxin structures by Pseudomonads was attempted as a biological detoxifiying process of mycotoxins. Firstly, when any variation of aflatoxin yield of Aspergillus parasiticus in a mixed culture with Pseudomonas aeruginosa was examined, there was no noticible effect by growth of Pseudomonads on aflatoxin yield of Asperillus sp. Secondly, when capacity of Pseudomonas aeruginosa utilizing aflatoxin as a carbon source for its growth was tested, there was some indication that aflatoxin might be used for growth of Pseudomonads. It was also noticed that the residual aflatoxin showed different migrating pattern compared with that of the intact aflatoxin by thin layer chromatography. Thirdly, the cell-free extract prepared from Pseudomonas aeruginosa grown in a glucose minimal medium supplemented with aflatoxin and the intact aflatoxins were incubated in the presence of $Mg^{++}$. After a certain length of incubation period, the reaction mixtures were applied on TLC plates. As a result, aflatoxins in the reaction mixture migrated differently as the control did. Such results may indicate that some changes of aflatoxin properties were induced by Pseudomonads.

• 한국토양비료학회지
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• 제48권2호
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• pp.119-124
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• 2015

Pyoverdines (PVDs) are organic compounds produced by the fluorescent Pseudomonads under iron starvation conditions. Among the isolated rhizosphere pseudomonads strains, P. putida KNUK9 showed the highest production of PVDs and its production reached to 62.81% siderophores units. DNA isolation, ligation, PCR amplification, and transformation using E. coli $DH5{\alpha}$ cells were carried out for preparing the strong pyoverdine producer strains. We detected seven genes playing the fundamental roles in the pyoverdine metabolism in Pseudomonads. According to data and analysis obtained from the study, we deduced that the strain P. putida KNUK9 contains the essential genes required for pyoverdine biosynthesis.

• 한국균학회지
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• 제45권4호
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• pp.370-376
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• 2017

양송이 재배에서 큰 피해를 주고 있는 세균성갈색무늬병(bacterial brown blotch disease)을 유발하는 3가지 병원균에 대해 양송이가 가지는 내성이 후세대에 전달되는지 검증한 결과는 다음과 같았다. 세균성갈색무늬병에 대한 양송이의 내성 정도는 균사생장능력과 상관관계가 없었다. 세균성갈색무늬병에 내성이 강하였던 계통의 후세대 단포자들은 균사체 단계에서는 부모세대처럼 강한 내성을 보이지 않으며, 자실체에서는 균사체에 비해 내성은 감소하였다. 세균성갈색무늬병에 내성이 약하였던 계통의 후세대 단포자들은 균사체 단계에서는 부모세대와 마찬가지로 내성이 매우 약하여, 부모세대가 가진 내성이 후세대로 전달되는 것으로 추측되었다. 자실체에서의 내성은 균사체에서 내성 유무와는 상관관계가 없었다. 따라서 자실체의 갈변 현상은 다른 요인이 복합적으로 관여하여 유발될 것으로 판단된다. Pseudomonas tolaasii는 자실체에서 Pseudomonas agarici에 비해서 갈변을 더 높게 유발시켰으며, Pseudomonas reactans는 균사체에는 큰 영향을 주지 못했지만, 자실체의 갈변에는 영향을 주었다. P. agarici는 자실체보다 균사체 생장억제능이 높았다.

• Journal of Applied Biological Chemistry
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• 제48권2호
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• pp.79-83
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• 2005

While screening for nematicidal activity of bacterial origins, various pseudomonads strains were inhabited in tomato rhizosphere. One isolate designated as $PE_{10}$ was selected for studies on nematicidal properties and plant growth-promoting (PGP) activity and was identified as Pseudomonas aeruginosa based on morphological features, biochemical and physiological tests, and carbohydrate utilization. To investigate nematicidal activity, Meloidogyne incognita juvenile mortality was determined using $PE_{10}$ culture filtrate. Inhibition of strain $PE_{10}$ against Fusarium oxysporum was observed using dual culture technique. Strain $PE_{10}$ showed good siderophore activity, HCN and IAA production abilities, and growth and development enhancement of tomato.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.897-898
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• 2005

• 한국식물병리학회지
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• 제13권3호
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• pp.160-166
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• 1997

전국에서 채집한 균주들 중 근권정착능력이 있는 균주를 선발하였다. 선발된 대부분의 균주들은 형광성 Pseudomonas속에 속하는 균주들이어고 이들 중 근권정착능력이 아주 우수한 B16과 V13을, 정착능력이 낮은 MC07과 X01을 시험에 공시하였다. 근권정착능력이 우수한 균주 B16과 V13은 종자 발아 초기단계에서의 증식 능력이 우수할 뿐만 아니라, 종자가 발아를 시작하여 유근이 나오는 시기에 이들의 정착밀도가 높았으며, 96시간이 지난 후에도 뿌리의 근단 부위에서 V13과 B16 균주들의 정착밀도가 높았다. 주사전자현미경(SEM)을 통하여 이들의 근권에서의 정착양상을 관찰한 결과, 정착능력이 우수한 균주들은 뿌리의 전반적인 부분에서 증식하고 근단 부위로 이동하는 것을 관찰할 수 있었다. 그러나 정착능력이 낮은 균주들은 유근의 표면에 산발적으로 흩어져 증식한 것을 볼 수 있었다.

• 미생물학회지
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• 제30권4호
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• pp.286-290
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• 1992

광주근교 지역의 근권 토양으로부터 cetrimide agar medium을 이용하여 형광성 pseudomonads를 분리하였고, CAS medium에서 siderophore의 생성능력이 우수한 pseudomonads만을 분리하여 생리화학적인 실험을 수행하였다. Kanamycin-sensitive pseudomonads를 Tn5를 이용한 mutagenesis를 실시하여 Kanamycin에 내성을 갖는 transconjugants를 선별하였고, siderophore 생합성을 하지 못하는 돌연변이주를 선별하기 위하여 CAS medium에서 yellow hallow를 형성하지 못하거나 King's B medium에서 형광성을 나타내지 못하는 colony를 선별하였다. 선별된 mutants들의 genomic DNA에 Tn5가 삽입되었는지를 확인하기 위하여 Southern blot hybridization을 실시한 결과 intact Tn5에 homology를 나타내는 하나의 single band를 확인하였다.