• Korean Journal of Soil Science and Fertilizer
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• v.48 no.2
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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.

• The Plant Pathology Journal
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• v.36 no.5
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• pp.491-496
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• 2020

An understanding of the contribution of secondary metabolites (SMs) to the antagonistic and biocontrol activities of bacterial biocontrol agents serves to improve biocontrol potential of the strain. In this study, to evaluate the contribution of each SM produced by Pseudomonas fluorescens NBC275 (Pf275) to its antifungal and biocontrol activity, we combined in silico analysis of the genome with our previous study of transposon (Tn) mutants. Thirteen Tn mutants, which belonged to 6 biosynthetic gene clusters (BGCs) of a total 14 BGCs predicted by the antiSMASH tool were identified by the reduction of antifungal activity. The biocontrol performance of Pf275 was significantly dependent on 2,4-diacetylphloroglucinol and pyoverdine. The clusters that encode for arylpolyene and an unidentified small linear lipopeptide influenced antifungal and biocontrol activities. To our knowledge, our study identified the contribution of SMs, such as a small linear lipopeptide and arylpolyene, to biocontrol efficacy for the first time.

• Korean Journal of Microbiology
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• v.55 no.2
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• pp.157-159
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• 2019

Pseudomonas fluorescens NBC275 (Pf275) isolated from soil sample collected at riverside of Nakdonggang showed antagonistic activity against fungal pathogens of plants and insects. Here we present complete genome sequence of Pf275. The genome comprises of 6,610,362 bp with GC content of 60.9%, which includes 5,869 predicted protein-coding genes, 16 rRNAs, and 65 tRNAs. Genome analysis revealed gene clusters encoding antimicrobial secondary metabolites such as pyoverdine, 2, 4-diacetylphloroglucinol, and phenazine, which are known to play essential roles in biocontrol of diseases.

• Korean Journal of Microbiology
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• v.55 no.3
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• pp.286-288
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• 2019

Pseudomonas parafulva PpaJBCS1880 (PpaJBCS1880) isolated from rice seeds showed strong antagonistic activity against bacterial plant pathogens by producing lipopeptide. Furthermore, the strain controlled the incidence of bacterial pustule in soybean plants and promoted the growth of rice plants. Here we present complete genome sequence of PpaJBCS1880. The genome comprises of 5,208,480 bp with GC content of 63.4%, which includes 4,487 predicted protein-coding genes, 19 rRNAs, and 74 tRNAs. Genome analysis revealed genes encoding antimicrobial secondary metabolites such as lipopeptide, pyoverdine, phenazine, and hydrogen cyanide, which are known to play essential roles in biocontrol of plant diseases.

• The Plant Pathology Journal
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• v.29 no.3
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• pp.323-329
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• 2013

The stationary-phase sigma factor, RpoS, influences the expression of factors important in survival of Pseudomonas chlororaphis O6 in the rhizosphere. A partial proteomic profile of a rpoS mutant in P. chlororaphis O6 was conducted to identify proteins under RpoS regulation. Five of 14 differentially regulated proteins had unknown roles. Changes in levels of proteins in P. chlororaphis O6 rpoS mutant were associated with iron metabolism, and protection against oxidative stress. The P. chlororaphis O6 rpoS mutant showed increased production of a pyoverdine-like siderophore, indole acetic acid, and altered isozyme patterns for peroxidase, catalase and superoxide dismutase. Consequently, sensitivity to hydrogen peroxide exposure increased in the P. chlororaphis O6 rpoS mutant, compared with the wild type. Taken together, RpoS exerted regulatory control over factors important for the habitat of P. chlororaphis O6 in soil and on root surfaces. The properties of several of the proteins in the RpoS regulon are currently unknown.

• The Plant Pathology Journal
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• v.17 no.3
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• pp.174-179
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• 2001

The plant growth-promoting Pseudomonas strains, WR8-3 (Pseudomonas fluorescens), WR9-11 (Pseudomonas sp.) and WR9-16 (P.putida), which induced resistance systematically in watermelon to gummy stem rot were investigated on their induced systemic resistance(ISR)-related characteristics. The pyoverdine production was repressed in the standard succinate medium by increasing the concentration of $\textrm{FeCL}_3$. But the iron-binding ability on chrome azurol S agar media (CAS) was observed only in the strains, WR8-3 and WR9-16. When the two strains were mutated, the resulting iron-binding siderophore-negative mutants, WR8-3m and WR 9-16m, failed to promote the growth of watermelon and to induce resistance. The strains, WR8-3 and WR 9-16, slightly inhibited the growth of Didymella bryoniae at a low concentration of $\textrm{FeCL}_3$ on Kong's medium B, but not to exert control dffect. The strain WR9-11 showed antagonism in the concentration of $\textrm{FeCL}_3$ from 0 to $1,000\mu\textrm{M}$. When the crude lipoplysaccharide of each strain was treated in the rhizosphere of watermelon, mean lesion area was similar to that of the untreated control. The strains, WR9-11 and WR9-16 produced some level of hydrogen cyanide (HCN). Salicylic acid production was not detected in all of the strains.