• 한국토양비료학회지
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• 제49권3호
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• pp.251-258
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• 2016

A rhizobacterium LPN-2, which showed strong antifungal activity and auxin producing ability, was isolated from a farmland in North Gyeongsang Province, South Korea. Based on analysis of the 16S rDNA sequence, strain LPN-2 was identified as a novel strain of Burkholderia and was designated as Burkholderia sp. LPN-2. In vitro experiments showed that the isolated stain LPN-2 significantly produced auxin within 48 hr incubation. In order to check for PGPR function we performed in vivo growth promoting test in different crops, including mung bean, pea and cabbage. Application of Burkholderia sp. LPN-2 showed dramatic growth promoting effect on all the tested plants. We also confirmed siderophore and cellulase productions by Burkholderia sp. LPN-2 using CAS blue agar and CMC plate test. Further treatment with LPN-2 and the crude culture broth was effective in suppressing anthracnose in vitro test and also reduced incidence and severity of anthracnose in apple and pepper. Taken together, we conclude that Burkholderia sp. LPN-2 might be used as organic fertilizer for effective crop production in organic farming.

• KSBB Journal
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• 제31권1호
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• pp.58-65
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• 2016

In this study, Arthrobacter scleromae SYE-3, which was isolated from indigenous plant in a subtropical region, Neigeria, with plant growth promoting activity was evaluated to determine the optimal culture condition. A bacterial strain SYE-3 had the IAA productivity ($89.15{\pm}0.36mg/L$) and ACC deaminase activity ($0.20{\pm}0.06$ at 72 hours). Also, optimal culture conditions such as temperature and pH of strain SYE-3 were $20^{\circ}C$ and 10 in LB medium, respectively. Strain SYE-3 had up to 3% salt tolerance in the LB medium. Plant growth promoting ability of strain SYE-3 using yam (Dioscorea japonica Thunb.) was evaluated. As a result, strain SYE-3 had showed very powerful effect on the increase of the shoot length and root biomass of yam (190.0% and 282.41% increase for 112 days, respectively). These results indicated that Arthrobacter scleromae SYE-3 can serve as a promising microbial resource for the biofertilizers of subtropical crops.

• Journal of Microbiology and Biotechnology
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• 제22권10호
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• pp.1375-1380
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• 2012

We previously isolated a rhizobacterium (Bacillus subtilis IJ-31) and demonstrated that its associated allelochemicals could indicate plant growth retardation. However, little is known about how the growth of plants is regulated by B. subtilis IJ-31 and its allelochemicals. In this study, we investigated whether plant growth retardation in this relationship occurred through the inhibition of gibberellin (GA) biosynthesis. GA $3{\beta}$-hydroxylase activity was found to be inhibited by B. subtilis IJ-31 and hydrocinnamic acid (HCA), which is one of the allelochemicals produced by B. subtilis IJ-31. Additionally, thin layer chromatography (TLC) demonstrated that B. subtilis IJ-31 culture broth and HCA both inhibit GA $3{\beta}$-hydroxylase (MBP-GA4) activity. The retardation of plants by HCA was then confirmed in vivo and in vitro using a Ryegrass and Arabidopsis growth retardation assay. Furthermore, treatment with either B. subtilis IJ-31 culture extract or its allelochemicals resulted in significant down-regulation of XTR9 gene expression in Arabidopsis. Overall, we identified the functional mechanism of plant growth retardation by B. subtilis IJ-31 and its allelochemicals.

• 미생물학회지
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• 제55권3호
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• pp.300-302
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• 2019

제천에서의 콩 근권 시료로부터 분리한 Glutamicibacter halophytocola DR408 균주는 내건성 식물생장촉진력을 보이고 있다. 본 연구에서 DR408 균주의 완전한 유전체 서열을 해독한 결과, 유전체의 크기는 3.77 Mbp였으며, G + C 함량이 60.2%였다. 또한 총 3,352개의 유전자 서열과 65개의 tRNA, 19개의 rRNA, 3개의 ncRNA가 존재하였다. 유전체 분석을 통해 식물의 내건성을 향상시킬 수 있는 삼투질 합성과 식물생장촉진 효소를 코딩하는 유전자를 다수 포함하는 것을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제16권3호
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• pp.450-456
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• 2006

Pseudomonas fluorescens MC07 is a growth-promoting rhizobacterium that suppresses mycelial growth in fungi such as Rhizoctonia solani, Pythium ultimum, Fusarium oxysporum, and Phytophthora capsici. To determine the role of the bacterium's antifungal activity in disease suppression, we screened 2,500 colonies generated by Tn5lacZ insertions, and isolated a mutant 157 that had lost antifungal activity. The EcoRI fragment carrying Tn5lacZ was cloned into pBluescript II SK(+) and used as a probe to isolate wild-type clones from a genomic library of the parent strain, MC07. Two overlapping cosmid clones, pEH4 and pEH5, that had hybridized with the mutant clone were isolated. pEH4 conferred antifungal activity to the heterologous host P.fluorescens strain 1855.344, whereas pEH5 did not. Through transposon mutagenesis of pEH4 and complementation analyses, we delineated the 14.7-kb DNA region that is responsible for the biosynthesis of an antifungal compound. DNA sequence analysis of the region identified 11 possible open reading frames (ORF), ORF1 through ORF11. A BLAST search of each putative protein implied that the proteins may be involved in an antifungal activity similar to polyketides.

• 한국미생물·생명공학회지
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• 제36권4호
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• pp.326-335
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• 2008

Bacillus subtilis AH18균주는 auxin, siderophore 그리고 cellulase를 동시에 생산하는 PGPR 균주이자 생물방제균주로 항진균성 siderophore의 특성을 확인한 결과 catechol type의 siderophore로 확인하였다. $Siderophore_{AH18}$ 의 정제는 Amberlite XAD-2, sephadex LH-20 column chromatography 그리고 HPLC를 통해 정제 및 정제여부를 확인하였으며, GC-MS, $^1H$-NMR, 그리고 $^{13}C$-NMR을 통해 구조 및 분자량을 확인하였다. 그 결과 B. subtilis AH18이 생산하는 siderophore은 분자량 883의 bacillibactin임을 확인하였으며, 포자발아억제활성을 나타냄을 확인하였다. B. subtilis AH18은 P. capsici에 의한 고추역병을 효과적으로 방제하였으며(방제력 55%), 이는 bacillibactin에 의한 효과가 포함되리라 추측된다.

• Journal of Microbiology and Biotechnology
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• 제21권4호
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• pp.379-386
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• 2011

The objective of this work was to investigate the ability of the plant growth-promoting rhizobacterium Pseudomonas aureofaciens 63-28 to induce plant defense systems, including defense-related enzyme levels and expression of defense-related isoenzymes, and isoflavone production, leading to improved resistance to the phytopathogen Rhizoctonia solani AG-4 in soybean seedlings. Seven-day-old soybean seedlings were inoculated with P. aureofaciens 63-28, R. solani AG-4, or P. aureofaciens 63-28 plus R. solani AG-4 (P+R), or not inoculated (control). After 7 days of incubation, roots treated with R. solani AG-4 had obvious damping-off symptoms, but P+R-treated soybean plants had less disease development, indicating suppression of R. solani AG-4 in soybean seedlings. Superoxide dismutase (SOD) and catalase (CAT) activities of R. solani AG-4-treated roots increased by 24.6% and 54.0%, respectively, compared with control roots. Ascorbate peroxidase (APX) and phenylalanine ammonia lyase (PAL) activities of R. solani AG-4-treated roots were increased by 75.1% and 23.6%, respectively. Polyphenol oxidase (PPO) activity in soybean roots challenged with P. aureofaciens 63-28 and P+R increased by 25.0% and 11.6%, respectively. Mn-SOD (S1 band on gel) and Fe-SOD (S2) were strongly induced in P+R-treated roots, whereas one CAT (C1) and one APX (A3) were strongly induced in R. solani AG-4- treated roots. The total isoflavone concentration in P+Rtreated shoots was 27.2% greater than the control treatment. The isoflavone yield of R. solani AG-4-treated shoots was 60.9% less than the control.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.1001-1010
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• 2005

Bacillus megaterium KL39, an antibiotic-producing plant growth promoting rhizobacterium (PGPR), was selected from soil. The antifungal antibiotic, denoted KL39, was purified from culture filtrate by column chromatography using Dion HP-20, Silica gel, Sephadex LH-20, and prep-HPLC. Thin layer chromatography, employing the solvent system of ethanol:ammonia:water=8:1:1, showed the $R_{f}$. value of 0.32. The antibiotic KL39 showed a negative reaction with ninhydrin solution, positive with iodine vapor, and also positive with Ehrlich reagent. It was soluble in methanol, ethanol, butanol, and acetonitrile, but insoluble in chloroform, toluene, hexane, ethyl ether, or acetone. Its UV spectrum had the maximum absorption at 208 nm. Amino acid composition, FAB-mass, $^{1}H-NMR,\;^{13}C-NMR$, and atomic analyses showed that the antibiotic KL39 (MW=1,071) has a structure very similar to iturin E. The antibiotic KL39 has a broad antifungal spectrum against a variety of plant pathogenic fungi including Rhizoctonia solani, Pyricularia oryzae, Monilinia froeticola, Botrytis cinenea, Altenaria kikuchiana, Fusarium oxysporum, and F. solani. An MIC value of $10\;{\mu}g/ml$ was determined for Phytophthora capsici. Macromolecular incorporation studies with P. capsici using radioactive [$^{3}H-adenine$] as the precursor, indicated that the antibiotic KL39 strongly inhibits the DNA biosynthesis of the fungal cell. Microscopic observation of the antifungal action showed abnormal hyphal swelling of P. capsici. The purified antibiotic KL39 was very effective for the biocontrol of in vivo Phytophthora-blight disease of pepper.

• Journal of Microbiology and Biotechnology
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• 제12권2호
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• pp.249-257
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• 2002

Pseudomonas fluorescens GL20 is a plant growth-promoting rhizobacterium that produces a large amount of hydroxamate siderophore under iron-limited conditions. The strain GL20 considerably inhibited the spore germination and hyphal growth of a plant pathogenic fungus, Fusarium solani, when iron was limited, significantly suppressed the root-rot disease on beans caused by F. solani, and enhanced the plant growth. The mechanism for the beneficial effect of strain GL20 on the disease suppression was due to the siderophore production, evidenced by mutant strains derived from the strain. Analysis of the outer membrane protein profile revealed that the growth of strain GL20 induced the synthesis of specific iron-regulated outer membrane proteins with molecular masses of 85- and 90 kDa as the high-affinity receptors for the ferric siderophore. In addition, a cross-feeding assay revealed the presence of multiple inducible receptors for heterologous siderophores in the strain. In order to induce increased efficacy and potential in biological control of plant disease, a siderophore-overproducing mutant, GL20-S207, was prepared by NTG mutagenesis. The mutant GL20-S207 produced nearly 2.3 times more siderophore than the parent strain. In pot trials of beans with F. solani, the mutant increased plant growth up to 1.5 times compared with that of the parent strain. These results suggest that the plant growth-promoting P. fluorescens GL20 and the genetically bred P. fluorescens GL20-S207 can play an important role in the biological control of soil-borne plant diseases in the rhizosphere.

• 한국미생물·생명공학회지
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• 제35권1호
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• pp.58-65
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• 2007

중금속으로 오염된 토양을 정화하기 위한 rhizoremediation 기법에서 식물이 중금속을 흡수하고 이동시키는 효율을 증가시키기 위하여 토양 미생물 특히, 근권세균의 역할이 중요하다. 이를 위하여 본 연구에서는 정유공장 주변의 유류 및 중금속으로 장기간 오염된 토양에서 서식하는 4가지 식물의 근권토양으로부터 Methylobacterium sp. SY-NiR1 균주를 분리하였다. 분리한 Methylobacterium sp. SY-NiR1는 분홍색 콜로니 형성, 막대모양 및 $\alpha-proteobacteria$에 속하는 특성으로 보아 pink-pigmented facultative methylotroph인 것으로 사료된다. 이 균주는 식물성호르몬인 indole acetic acid(IAA) 생산능을 가지고 있으며, 카드뮴, 크롬, 구리, 납, 니켈 그리고 아연 등과 같은 다양한 중금속에 대하여 내성을 가지고 있었으며, $EC_{50}$을 기준으로 한 SY-NiR1의 중금속에 대한 내성은 Zn > Ni > Cu > Pb > Cd > Cr 순이다. 따라서 본 연구에서 분리한 Methylobacterium sp. SY-NiR1 균주는 중금속으로 오염된 토양에서 식물의 발아, 생장 및 발달을 도와 식물의 중금속 흡수를 증가시켜 rhizorememdiation 효율을 증가시킬 수 있을 것으로 기대된다.