• Journal of Microbiology and Biotechnology
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• 제20권11호
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• pp.1577-1584
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• 2010

In total, 140 halotolerant bacterial strains were isolated from both the soil of barren fields and the rhizosphere of six naturally growing halophytic plants in the vicinity of the Yellow Sea, near the city of Incheon in the Republic of Korea. All of these strains were characterized for multiple plant growth promoting traits, such as the production of indole acetic acid (IAA), nitrogen fixation, phosphorus (P) and zinc (Zn) solubilization, thiosulfate ($S_2O_3$) oxidation, the production of ammonia ($NH_3$), and the production of extracellular hydrolytic enzymes such as protease, chitinase, pectinase, cellulase, and lipase under in vitro conditions. From the original 140 strains tested, on the basis of the latter tests for plant growth promotional activity, 36 were selected for further examination. These 36 halotolerant bacterial strains were then tested for 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. Twenty-five of these were found to be positive, and to be exhibiting significantly varying levels of activity. 16S rRNA gene sequencing analyses of the 36 halotolerant strains showed that they belong to 10 different bacterial genera: Bacillus, Brevibacterium, Planococcus, Zhihengliuella, Halomonas, Exiguobacterium, Oceanimonas, Corynebacterium, Arthrobacter, and Micrococcus. Inoculation of the 14 halotolerant bacterial strains to ameliorate salt stress (150 mM NaCl) in canola plants produced an increase in root length of between 5.2% and 47.8%, and dry weight of between 16.2% and 43%, in comparison with the uninoculated positive controls. In particular, three of the bacteria, Brevibacterium epidermidis RS15, Micrococcus yunnanensis RS222, and Bacillus aryabhattai RS341, all showed more than 40% increase in root elongation and dry weight when compared with uninoculated salt-stressed canola seedlings. These results indicate that certain halotolerant bacteria, isolated from coastal soils, have a real potential to enhance plant growth under saline stress, through the reduction of ethylene production via ACC deaminase activity.

• Journal of Microbiology and Biotechnology
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• 제16권10호
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• pp.1650-1655
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• 2006

Bacteria belonging to the genus Paenibacillus are facultatively anaerobic endospore formers and are attracting growing ecological and agricultural interest, yet their genome information is very limited. The present study surveyed the genomic features of P. polymyxa ATCC $842^T$ using pulse-field gel electrophoresis of restriction fragments and sample genome sequencing of 1,747 reads (approximately 17.5% coverage of the genome). Putative functions were assigned to more than 60% of the sequences. Functional classification of the sequences showed a similar pattern to that of B. subtilis. Sequence analysis suggests nitrogen fixation and antibiotic production by P. polymyxa ATCC $842^T$, which may explain its plant growth-promoting effects.

• The Plant Pathology Journal
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• 제25권4호
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• pp.389-399
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• 2009

A group of beneficial plant bacteria has been shown to increase crop growth referring to as plant growth-promoting rhizobacteria (PGPR). PGPR can decrease plant disease directly, through the production of antagonistic compounds, and indirectly, through the elicitation of a plant defense response termed induced systemic resistance (ISR). While the mechanism of PGPR-elicited ISR has been studied extensively in the model plant Arabidopsis, it is less well characterized in crop plants such as pepper. In an effort to better understand the mechanism of ISR in crop plants, we investigated the induction of ISR by Bacillus cereus strain BS107 against Xanthomonas axonopodis pv. vesicatoria in pepper leaves. We focused on the priming effect of B. cereus strain BS107 on plant defense genes as an ISR mechanism. Of ten known pepper defense genes that were previously reported to be involved in pathogen defense signaling, the expression of Capsicum annum pathogenesis-protein 4 and CaPR1 was systemically primed by the application of strain BS107 onto pepper roots confirming by quantitative-reverse transcriptase PCR. Our results provide novel genetic evidence of the priming effect of a rhizobacterium on the expression of pepper defense genes involved in ISR.

• 한국미생물·생명공학회지
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• 제40권3호
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• pp.261-267
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• 2012

본 연구에서는 경기도 궁평항 지역의 해안사구에 서식하고 있는 토착식물 6종(Rorippa islandica, Rumex crispus, Artemisia princeps var. orientalis, Lilium sp Stellaria media, and Gramineae)의 식물 뿌리와 근권토양으로부터 colony library를 구축하여 식물성장촉진 능력과 내염능을 평가하였다. 분리한 근권세균 중 4.0%의 염분이 존재하는 환경에서 50% 이상의 세균이 염분에 강한 내성을 가지고 있었다. 95개의 균주를 대상으로 식물성호르몬인 IAA생산능을 가지는 균주는 근권토양에서는 13.9%, 식물뿌리에서는 7.6%였으며, 1-aminocyclopropane-1-carboxylic acid (ACC)를 제거하는 ACC deaminase 활성을 가진 균주는 근권토양에서는 55.8%, 뿌리에서는 36.6%였다. 또한, Siderphores 합성능을 가지고 있는 균주는 근권에서 62.7%, 뿌리에서는 50%를 차지하였다. 식물성장촉진능과 내염능을 가진 세균을 대상으로 상관관계를 분석한 결과, ACC deaminase 활성과 siderphore(s) 합성능 사이에는 양의 상관관계를 형성하였고(r=0.605, p<0.037), 염분 내성능과 ACC deaminase 활성, 염분 내성능과 siderphore(s) 합성능 사이에도 양의 상관관계를 형성하였다(r=0.762, p<0.004, r=0.771, p<0.003, 각각).

• The Plant Pathology Journal
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• 제18권2호
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• pp.57-62
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• 2002

In vivo expression technology (IVET) has been developed to study bacterial gene expression in Salmonella typhimurium during host infection. The expression of selected genes by IVET has been elevated in vivo but not in vitro. The selected genes turned out to be important for bacterial virulence and/or pathogenicity. IVET depends on a synthetic operon with a promoterless transcriptional fusion between a selection marker gene and a reporter gene. The IVET approach has been successfully adapted in other bacterial pathogens and plant-associated bacteria using different selection markers. Pseudomonas putida suppresses citrus root rot caused by Phytophthora parasitica and enhances citrus seedling growth. The WET strategy was adapted based on a transcriptional fusion, pyrBC'-lacZ, in P. putida to study the bacterial traits important far biocontrol activities. Several genes appeared to be induced on P. parasitica hyphae and were found to be related with metabolism and regulation of gene expression. It is likely that the biocontrol strain took a metabolic advantage from the plant pathogenic fungus and then suppressed citrus root rot effectively. The result was parallel with those from the adaptation of IVET in P. fluorescens, a plant growth promoting rhizobacteria (PGPR). Interestingly, genes encoding components for type III secretion system have been identified as rhizosphere-induced genes in the PGPR strain. The type III secretion system may play a certain role during interaction with its counterpart plants. Application of IVET has been demonstrated in a wide range of bacteria. It is an important strategy to genetically understand complicated bacterial traits in the environment.

• 한국미생물·생명공학회지
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• 제36권4호
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• pp.268-275
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• 2008

경북포항지역의 해안사구지역에서 서식하는 11종의 해안사구 식물의 근권으로부터 1,330균주의 근권세균들을 분리하였다. 이들 분리된 근권세균등 중에서 9종의 주요 식물병원성 진균인 Phytophthora capsici, Fusarium oxysporum, Corynespora casriicola, Colletotrichum acutatum, Botrytis cinerea, Rhizoctonia solani AG-1(IA), Pythium ultimum, Rhizoctonia solani AG-1(IB)에 대하여 넓은 항진균성 스펙트럼을 가지고 동시에 생장촉진호로몬 옥신을 생산하는 23균주의 근권세균을 선발하였다. 1차 선발된 23균주의 옥신 생산성 사구식물근권세균들에서 19균주가 항진균성 siderophore를, 4균주가 항진균성 cellulase를 생산할 수 있었으며, 17균주는 불용성 인산염을 분해할 수 있었다. 또, 23균주의 선발된 사구식물생장 촉진 근권세균들은 16S rDNA 염기서열 조사와 Bergey's manual에 의하여 99%이상의 상동성을가지는 7균주의 Bacillus sp.균주들과 15균주 Pseudomonas sp.균주들로 동정할 수 있었다. 한편, 이들 중 다기능 사구식물생장촉진 근권세균인 Pseudomonas fluorescens IB4-14는 고염, 건조와 같은 환경스트레스에 저항성을 가질 수 있게 하는 ACC deaminase를 생산하므로써 식물생장촉진은 물론이고, 환경스트레스 저항성 기작을 가지는 다중기능 균주이었다. 또한, 선발된 옥신생산성 다기능 균주인 P. fluorescens IB4-14는 사구식물인 갯까치수영의 종자발아능과 뿌리생장촉진능에서 우수한 생육촉진능을 발휘함을 확인하였으므로 사구식물 복원에 사용할 미생물제제의 구성균주로 선발되었다고 생각한다.

• 한국미생물·생명공학회지
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• 제48권1호
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• pp.38-47
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• 2020

본 연구는 토양으로부터 분리한 균주를 대상으로 식물병 방제활성 및 식물 생장촉진 활성을 확인하고자 하였다. 식물병원성 곰팡이에 대한 길항능을 통해 방제기능을 확인할 수 있었으며, 이는 siderophore 및 항생물질 생성 등에 기인되는 것으로 판단된다. 또한 ANG40의 경우에는 amylase, cellulase, xylanase와 같은 세포외 효소활성을 갖고 있음을 확인하였다. 이 외에도 질소 고정능, 인산 가용화능, siderophore 생성능 등 다양한 실험을 통해 식물 생장에 필수적인 질소, 인, 철 등을 식물이 흡수 가능한 형태로 변화시켜 식물 생장에 도움을 줄 수 있을 것으로 기대된다. 또한 6종의 분리균주는 모두 에틸렌 생성과 연관된 IAA를 생성하였으며, 그 중에서도 ANG51의 경우에는 ACC deaminase 활성도 갖고 있음을 확인하였다. 따라서, 최종 선별된 Pseudomonas geniculata ANG3, Exiguobacterium acetylicum ANG40, Burkholderia stabilis ANG51을 이용하여 식물 생장촉진 활성과 식물 병원성 곰팡이에 항진균 활성을 갖는 새로운 생물학적 제제로써 이용 가능성을 제시하였다.

• Mycobiology
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• 제35권3호
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• pp.129-134
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• 2007

Systemic effect of two plant growth-promoting rhizobacterial (PGPR) strains, viz., Pseudomonas fluorescens (Pf4) and P. aeruginosa (Pag), was evaluated on pea (Pisum sativum) against the powdery mildew pathogen Erysiphe pisi. Foliar spray of the two PGPR strains was done on specific nodal leaves of pea and conidial germination of E. pisi was observed on other nodal leaves, distal to the treated ones. Conidial germination was reduced on distant leaves and at the same time, specific as well as total phenolic compounds increased in the leaves distal to those applied with PGPR strains, thereby indicating a positive correlation. The strains induced accumulation of phenolic compounds in pea leaves and the amount increased when such leaves were get inoculated with E. pisi conidia. Between the two strains, Pag was found to be more effective than Pf4 as its effect was more persistent in pea leaves. Foliar application of PGPR strains for the control of powdery mildew of pea is demonstrated in vitro while correlating it with the increased accumulation of plant phenolics.

• Journal of Ginseng Research
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• 제45권2호
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• pp.218-227
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• 2021

Background: Panax ginseng is one of the most important medicinal plants and is usually harvested after 5 to 6 years of cultivation in Korea. Heavy metal (HM) exposure is a type of abiotic stress that can induce oxidative stress and decrease the quality of the ginseng crop. Siderophore-producing rhizobacteria (SPR) may be capable of bioremediating HM contamination. Methods: Several isolates from ginseng rhizosphere were evaluated by in vitro screening of their plant growth-promoting traits and HM resistance. Subsequently, in planta (pot tests) and in vitro (medium tests) were designed to investigate the SPR ability to reduce oxidative stress and enhance HM resistance in P. ginseng inoculated with the SPR candidate. Results: In vitro tests revealed that the siderophore-producing Mesorhizobium panacihumi DCY119^T had higher HM resistance than the other tested isolates and was selected as the SPR candidate. In the planta experiments, 2-year-old ginseng seedlings exposed to 25 mL (500 mM) Fe solution had lower biomass and higher reactive oxygen species level than control seedlings. In contrast, seedlings treated with 10⁸ CFU/mL DCY119^T for 10 minutes had higher biomass and higher levels of antioxidant genes and nonenzymatic antioxidant chemicals than untreated seedlings. When Fe concentration in the medium was increased, DCY119^T can produce siderophores and scavenge reactive oxygen species to reduce Fe toxicity in addition to providing indole-3-acetic acid to promote seedling growth, thereby conferring inoculated ginseng with HM resistance. Conclusions: It was confirmed that SPR DCY119^T can potentially be used for bioremediation of HM contamination.

• 한국미생물·생명공학회지
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• 제37권2호
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• pp.110-117
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• 2009

독도에 자생하고 있는 야생 가지과 식물근권세균들의 특성을 밝히기 위해 까마중을 채집하였다. 까마중 근권으로부터 총 44종의 포자형성세균 혹은 질소고정세균을 분리하였다. 이 균주들은 16S rDNA 염기서열을 이용하여 부분 동정하였다. PGPR로써의 특성을 밝히기 위해 옥신 생산능, 인 가용능, 그리고 Siderophore 형성능을 측정하였다. 식물 생장호르몬인 옥신을 형성하는 균주는 19종, 난분해성 인을 분해할 수 있는 균주는 8종, 식물병원균을 억제하는 siderophore를 형성할 수 있는 균주는 13종으로 확인되었다. 우리나라에서 널리 재배되고 있는 가지과식물인 담배와 고추에 직접 적용하여, 식물의 생장 촉진 효과 및 식물 전신유도저항성 효과를 확인하였다. 특히 KUDC1009는 식물의 생장 촉진 효과 그리고 식물병원균에 대한 저항성을 증가시키는 등 다기능의 능력을 가지는 것을 확인할 수 있었다. 독도의 근권세균들은 다양한 스트레스 환경하에서 야생 까마중이 생존하는데 많은 도움을 주는 것을 추측 할 수 있었다.