• Journal of Applied Biological Chemistry
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• 제56권4호
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• pp.235-239
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• 2013

녹비 작물인 헤어리베치의 간척지 적용을 위해 본 연구에서는 헤어리베치의 뿌리혹으로부터 분리 된 Rhizobium sp. RH84의 특성을 파악하고 이를 직접 간척지에 적용하여 헤어리베치의 생산량 증대에 이용하고자 하였다. 전보에서 분리 한 RH84의 형태학적, 생리학적 특성 및 식물생육촉진(PGP) 활성을 확인하기 위하여 옥신, 질소 고정능, 인산 가용능, sideropore 생산능을 분석하였다. 그 결과, RH84는 식물호르몬인 IAA를 $9.03{\mu}g/mL$ 생산하였고, 질소 고정 활성을 가진 균주이었다. 또한 염 농도가 0.3%인 간척지 토양에서의 헤어리베치 생장에 영향을 주며, 간척지 포장에서 약 56%의 헤어리베치 수확량을 증가시켰다. 따라서 Rhizobium sp. RH84 균주는 염 농도가 높은 간척지에서 녹비작물인 헤어리베치의 생장을 촉진시키며 수확량을 증가시키기 위한 균주임을 확인하였다.

• Journal of Ginseng Research
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• 제45권3호
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• pp.442-449
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• 2021

Background: Panax ginseng is an important crop in Asian countries given its pharmaceutical uses. It is usually harvested after 4-6 years of cultivation. However, various abiotic stresses have led to its quality reduction. One of the stress causes is high content of heavy metal in ginseng cultivation area. Plant growth-promoting rhizobacteria (PGPR) can play a role in healthy growth of plants. It has been considered as a new trend for supporting the growth of many crops in heavy metal occupied areas, such as Aluminum (Al). Methods: In vitro screening of the plant growth promoting activities of five tested strains were detected. Surface-disinfected 2-year-old ginseng seedlings were dipping in Rhizobium panacihumi DCY116^T suspensions for 15 min and cultured in pots for investigating Al resistance of P. ginseng. The harvesting was carried out 10 days after Al treatment. We then examined H₂O₂, proline, total soluble sugar, and total phenolic contents. We also checked the expressions of related genes (PgCAT, PgAPX, and PgP5CS) of reactive oxygen species scavenging response and pyrroline-5-carboxylate synthetase by reverse transcription polymerase chain reaction (RT-PCR) method. Results: Among five tested strains isolated from ginseng-cultivated soil, R. panacihumi DCY116^T was chosen as the potential PGPR candidate for further study. Ginseng seedlings treated with R. panacihumi DCY116^T produced higher biomass, proline, total phenolic, total soluble sugar contents, and related gene expressions but decreased H₂O₂ level than nonbacterized Al-stressed seedlings. Conclusion: R. panacihumi DCY116^T can be used as potential PGPR and "plant strengthener" for future cultivation of ginseng or other crops/plants that are grown in regions with heavy metal exposure.

• Journal of Microbiology and Biotechnology
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• 제27권10호
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• pp.1790-1797
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• 2017

In the present study, we demonstrate that the growth of salt-stressed pepper plants is improved by inoculation with plant growth-promoting rhizobacteria (PGPR). Three PGPR strains (Microbacterium oleivorans KNUC7074, Brevibacterium iodinum KNUC7183, and Rhizobium massiliae KNUC7586) were isolated from the rhizosphere of pepper plants growing in saline soil, and pepper plants inoculated with these PGPR strains exhibited significantly greater plant height, fresh weight, dry weight, and total chlorophyll content than non-inoculated plants. In addition, salt-stressed pepper plants that were inoculated with B. iodinum KNUC7183 and R. massiliae KNUC7586 possessed significantly different total soluble sugar and proline contents from non-inoculated controls, and the activity of several antioxidant enzymes (ascorbate peroxidase, guaiacol peroxidase, and catalase) was also elevated in PGPR-treated plants under salt stress. Overall, these results suggest that the inoculation of pepper plants with M. oleivorans KNUC7074, B. iodinum KNUC7183, and R. massiliae KNUC7586 can alleviate the harmful effects of salt stress on plant growth.

• 한국토양비료학회지
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• 제50권3호
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• pp.135-149
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• 2017

In order to obtain promising rice growth-promoting microbial strains that can be used as substitutes for chemical fertilizers, 172 bacterial strains were isolated from rice roots grown in Korean and Russian soils. Out of them, the strains KR076, KR083, KR181 and RRj228 showed plant growth-promoting activities on maize seedlings. Bacillus megaterium KR076 and Bacillus sp. KR083 showed both nitrogen-fixing and plant growth-promoting activities, while Rhizobium sp. KR181 and Pseudomonas sp. RRj228 appeared to support only plant growth-promotion, but not $N_2$ fixation. Especially, RRj228 showed high growth promoting activity at low concentrations. Inoculation studies with KR083 and RRj228 revealed a high affinity to the Japonica rice variety such as Junambyeo than the Korean Tongil type variety such as Arumbyeo. Both KR083 and RRj228 strains showed rhizoplane and/or endophytic colonization in Japonica and Tongil types rice when soaked with the bacterial suspension of $1.1{\times}10^5cfu\;ml^{-1}$ for six and twelve hours. However, the total bacterial cell numbers were higher in the roots of Japonica variety than in the Tongil type. In inoculation trials with Daesanbyeo rice variety, the seedlings inoculated with KR181 and RRj228 at the rate of $2.0{\times}10^6cfu\;ml^{-1}$ showed yield increment of 35% and 33% (p < 0.01), respectively, so that they contributed to the replacement of chemical fertilizer at half doses of N, $P_2O_5$, and $K_2O$ in pots. In Junambyeo rice seedlings, the strain RRj228, when inoculated with a cell suspension of $1.8{\times}10^6cfu\;ml^{-1}$, promoted 3.4% higher yield at 70% dose than at a full dose level of N $110kg\;ha^{-1}$ in field. These results suggest that the rhizobacteria KR181 and RRj228 are prospective strains for enhancing rice performance.

• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1614-1623
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• 2010

Bacteria were isolated from roots of sugarcane varieties grown in the fields of Punjab. They were identified by using API20E/NE bacterial identification kits and from sequences of 16S rRNA and amplicons of the cpn60 gene. The majority of bacteria were found to belong to the genera of Enterobacter, Pseudomonas, and Klebsiella, but members of genera Azospirillum, Rhizobium, Rahnella, Delftia, Caulobacter, Pannonibacter, Xanthomonas, and Stenotrophomonas were also found. The community, however, was dominated by members of the Pseudomonadaceae and Enterobacteriaceae, as representatives of these genera were found in samples from every variety and location examined. All isolates were tested for the presence of five enzymes and seven factors known to be associated with plant growth promotion. Ten isolates showed lipase activity and eight were positive for protease activity. Cellulase, chitinase, and pectinase were not detected in any strain. Nine strains showed nitrogen fixing ability (acetylene reduction assay) and 26 were capable of solubilizing phosphate. In the presence of 100 mg/l tryptophan, all strains except one produced indole acetic acid in the growth medium. All isolates were positive for ACC deaminase activity. Six strains produced homoserine lactones and three produced HCN and hexamate type siderophores. One isolate was capable of inhibiting the growth of 24 pathogenic fungal strains of Colletotrichum, Fusarium, Pythium, and Rhizoctonia spp. In tests of their abilities to grow under a range of temperature, pH, and NaCl concentrations, all isolates grew well on plates with 3% NaCl and most of them grew well at 4 to $41^{\circ}C$ and at pH 11.

• Journal of Microbiology and Biotechnology
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• 제20권11호
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• pp.1491-1499
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• 2010

Rhizosphere microorganisms possessing phytase activity are considered important for rendering phytate-phosphorus (P) available to plants. In the present study, the Citrobacter braakii phytase gene (appA) was overexpressed in rhizobacteria possessing plant growth promoting (PGP) traits, for increasing their potential as bioinoculants. AppA was cloned under the lac promoter in the broadhost-range expression vector pBBR1MCS-2. Transformation of the recombinant construct pCBappA resulted in high constitutive phytase activity in all of the eight rhizobacterial strains belonging to genera Pantoea, Citrobacter, Enterobacter, Pseudomonas (two strains), Rhizobium (two strains), and Ensifer that were studied. Transgenic rhizobacterial strains were found to display varying levels of phytase activity, ranging from 10-folds to 538-folds higher than the corresponding control strains. The transgenic derivative of Pseudomonas fluorescens CHA0, a well-characterized plant growth promoting rhizobacterium, showed the highest expression of phytase (~8 U/mg) activity in crude extracts. Although all transformants showed high phytase activity, rhizobacteria having the ability to secrete organic acid showed significantly higher release of P from Ca-phytate in buffered minimal media. AppA overexpressing rhizobacteria showed increased P content, and dry weight (shoot) or shoot/ root ratio of mung bean (Vigna radiata) plants, to different extents, when grown in semisolid agar (SSA) medium containing Na-phytate or Ca-phytate as the P sources. This is the first report of the overexpression of phytase in rhizobacterial strains and its exploitation for plant growth enhancement.

• 한국균학회지
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• 제43권4호
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• pp.253-259
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• 2015

고추 탄저병은 국내 고추재배에 가장 큰 피해를 일으키며, Colletotrichum acutatum이 주요 원인균이다. 본 연구에서는 포장에서 고추탄저병의 방제와 식물생장촉진효과를 선발된 길항미생물을 이용하여 평가하였다. 4개의 길항미생물은 이전 연구를 통하여 고추포장(GJ01, GJ11)과 갯벌(LB01, LB14)에서 선발하였다. 4개의 길항미생물은 대조균주 EXTN-1을 포함하여 C. acutatum과 대치배양에서 길항효과를 보였다. 식물생장촉진효과를 알아보기 위해 고추종자의 발아율과 초기생장효과, 그리고 포장에서 식물의 생장효과를 검정하였다. 그 결과 4개의 선발균주는 모두 식물생장효과가 있었다. 그 중에서도 GJ01은 초기생육에서 가장 높은 생장효과를 보였으며, GJ11은 포장에서 가장 높은 고추수확량을 얻었다. 그리고 포장에서 탄저병의 방제효과는 4개의 길항미생물 처리에 의해 63.2~72.5%의 방제가를 보였다. 현재 연구를 토대로 4개의 길항미생물은 고추 탄저병에 대한 잠재적인 생물학적 방제제로서의 가능성을 보여주었다.