• 한국토양비료학회지
• /
• 제29권2호
• /
• pp.190-198
• /
• 1996

Bradyrhizobium japonicum RJB6$str^rnal^r$에 neomycin resistant gene인 Tn5을 삽입한 표지균주를 사용하여 Pseudomonas fluorescens(PS-3)와 Bacillus subtilis(BCAC-4)를 대두에 혼합접종하고, 또한 항생제 처리후 표지균주를 접종한 대두의 생장 및 근류형성율을 조사 분석한 결과를 요약하면 다음과 같다. 1. 5년이상 대두 재배토양에 표지균주인 RJB6 $str^rnal^rneo^r$을 Ps-3와 혼합접종했을 때 접종근류균의 근류형성율은 8.5%, BCAC-4와 혼합접종한 경우는 4.3%였으나, 표지균주, Ps-3라 BCAC-4의 3 균주를 혼합접종했을 때는 2.9% 에 지나지 않았다. 2. 대두를 재배하지 않은 토양에 표지균주을 Ps-3와 혼합접종했을 때 접종근류균의 근류형성은 10.3%, BCAC-4와 혼합접종한 경우은 6%였으며, 표지균주와 Ps-3, BCAC-4의 3 균주를 혼합접종 했을 때 5.0%의 근류형성율을 나타냈다. 3. 혼합접종이 대두 생육상에 미치는 영향은 일반적으로 표지균주와 Ps-3의 혼합접종 처리구에서 가장 양호했다. 4. 항생제를 처리했을 때 5년 이상 대두재배 토양에서 접종근류균의 근류형성은 12.2-25.4% 였으며, 대두를 재배하지 않은 토양에서는 23.7-43.7% 였으나, 항생제 1,000ppm 처리구 에서 43.2%로 가장 높은 근류형성율을 보였다.

• Molecules and Cells
• /
• 제45권7호
• /
• pp.502-511
• /
• 2022

Bacterial volatile compounds (BVCs) exert beneficial effects on plant protection both directly and indirectly. Although BVCs have been detected in vitro, their detection in situ remains challenging. The purpose of this study was to investigate the possibility of BVCs detection under in situ condition and estimate the potentials of in situ BVC to plants at below detection limit. We developed a method for detecting BVCs released by the soil bacteria Bacillus velezensis strain GB03 and Streptomyces griseus strain S4-7 in situ using solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC-MS). Additionally, we evaluated the BVC detection limit in the rhizosphere and induction of systemic immune response in tomato plants grown in the greenhouse. Two signature BVCs, 2-nonanone and caryolan-1-ol, of GB03 and S4-7 respectively were successfully detected using the soil-vial system. However, these BVCs could not be detected in the rhizosphere pretreated with strains GB03 and S4-7. The detection limit of 2-nonanone in the tomato rhizosphere was 1 µM. Unexpectedly, drench application of 2-nonanone at 10 nM concentration, which is below its detection limit, protected tomato seedlings against Pseudomonas syringae pv. tomato. Our finding highlights that BVCs, including 2-nonanone, released by a soil bacterium are functional even when present at a concentration below the detection limit of SPME-GC-MS.

• 식물병연구
• /
• 제25권3호
• /
• pp.136-142
• /
• 2019

식물 근권과 내생에서 분리한 447 균주 중 식물 생장 촉진특성과 건조 내성이 있는 28 균주를 일차적으로 스크리닝 하였으며, PEG에 의한 인위적 건조 스트레스 조건에서 잎의 상대수분함량과 MDA를 기반으로 GLC02와 KJ40을 선발하였다. 이 두 균주의 효과를 검증하기 위해 밭흙을 사용한 자연 건조에서 식물 포트 검정을 하였으며, 기공전도도와 지상부(줄기와 잎) 무게가 유의하게 증가한 반면 MDA가 감소하였다. 병 억제 효과에서는 GLC02를 처리할 경우 역병의 병진전도가 감소하였으며, KJ40을 처리할 경우 세균성 점무늬병에 대한 억제효과가 있었다. 이를 토대로, GLC02와 KJ40을 처리할 경우 건조 스트레스를 경감시켜주며 식물생장의 증진, 병 억제효과를 유도하여 생물비료의 소재로 사용할 수 있을 것으로 생각된다.

• 한국미생물·생명공학회지
• /
• 제49권3호
• /
• pp.391-402
• /
• 2021

Earthworms play an important role in soil fertilization, interacting continually with microorganisms. This study aims to demonstrate the existence of beneficial microorganisms living in the earthworm's immune system, the coelomic fluid. To achieve this goal, a molecular identification technique was performed, using cytochrome c oxidase I (COI) barcoding to identify abundant endogenic earthworms inhabiting the temperate zone of Rabat, Morocco. Then, 16S rDNA and ITS sequencing techniques were adopted for bacteria and fungi, respectively. Biochemical analysis, showed the ability of bacteria to produce characteristic enzymes and utilize substrates. Qualitative screening of plant growth-promoting traits, including nitrogen fixation, phosphate and potassium solubilization, and indole acetic acid (IAA) production, was also performed. The result of mitochondrial COI barcoding allowed the identification of the earthworm species Aporrectodea molleri. Phenotypic and genotypic studies of the sixteen isolated bacteria and the two isolated fungi showed that they belong to the Pseudomonas, Aeromonas, Bacillus, Buttiauxella, Enterobacter, Pantoea, and Raoultella, and the Penicillium genera, respectively. Most of the isolated bacteria in the coelomic fluid showed the ability to produce β-glucosidase, β-glucosaminidase, Glutamyl-β-naphthylamidase, and aminopeptidase enzymes, utilizing substrates like aliphatic thiol, sorbitol, and fatty acid ester. Furthermore, three bacteria were able to fix nitrogen, solubilize phosphate and potassium, and produce IAA. This initial study demonstrated that despite the immune property of earthworms' coelomic fluid, it harbors beneficial microorganisms. Thus, the presence of resistant microorganisms in the earthworm's immune system highlights a possible selection process at the coelomic fluid level.

• 한국토양비료학회지
• /
• 제45권6호
• /
• pp.1037-1042
• /
• 2012

충남 부여군 석성면 양송이 재배 농가에서 채취한 양송이 수확 후 배지로부터 auxin생성능이 뛰어난 세균 2SJ8-02 균주를 분리하여 TLC 및 HPLC 분석을 통해 확인한 결과, IAA 생산농도는 $122mg\;L^{-1}$이었으며 LC-Mass분석에 의하여 생성된 물질은 분자량이 175인 IAA로 확인되었다. 분리균에 의한 IAA 생산을 위한 최적조건을 실험한 결과, 0.1% L-tryptophan를 함유한 pH 7.0의 R2A broth배지에 $35^{\circ}C$, 24시간 배양 시 최대 이었다. 녹두발근 생검법과 pot 재배를 통한 식물생육효과 실험에서 분리균 배양액의 첨가는 대조구에 비해 발근수와 뿌리길이에서 약 2배의 뿌리신장효과를 보였다. 생리적 특성 및 계통학적 특성분석을 통해 분리균은 Gram 음성 간균인 Pantoea rwandensis 2SJ8-02로 동정되었다.

• 한국균학회지
• /
• 제44권1호
• /
• pp.36-47
• /
• 2016

본 연구는 식물 근권에서 분리한 유용미생물 PA1, PA2, PA4, PA5, PA12 의 식물 생장 촉진능력과 식물 병원성 진균인 Colletotrichum acutatum, C. coccodes, C. gloeosporioides, C. dematium, Botrytis cinerea, Rhizoctonia solani, Sclerotinia minor 그리고 Fusarium sp.에 대한 생장억제능력을 평가하는데 그 목적이 있다. In vitro 실험에서 유용미생물의 식물 병원성 진균의 생장억제 능력을 확인하기 위해 세균배지인 TSA 배지와 곰팡이 배지인 PDA배지, 그리고 TSA와 PDA배지를 각각 50%씩 혼합한 배지(v/v, 1:1)에서 대치배양을 실시하였다. 그 결과 PDA배지에서는 PA2가 C. coccodes에 대해 65.5%로 가장 높은 억제능력을 보였으며, TSA배지에서는 PA2가 S. minor에 대해 96.5%로 가장 높은 억제력을 보였다. 또한 PDA와 TSA를 혼합한 배지에서는 PA2가 C. acutatum에 대해 58.5%로 가장 높은 억제능력을 보였다. 분리한 5균주 모두에서 식물병원성 진균에 대하여 생물적 방제 효과가 있음을 확인하였다. 또한 식물생장 촉진능력을 유발하는 원인물질을 탐색하기 위해 siderophore, protease, chitinase, hydrogen cyanide (HCN) 생성 유무를 확인하였고, phosphate solubilizing 실험을 실시하였다. 본 연구에서 사용된 유용미생물 5균주를 16s rDNA sequencing 결과 PA1, PA2는 Bacillus subtilis, PA4, PA5, PA12 각각 Bacillus altitudinis, Paenibacillus polymyxa, Bacillus amyloliquefaciens로 동정되었다.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2003년도 생물공학의 동향(XII)
• /
• pp.40-44
• /
• 2003

Soil-borne infectious disease including Pythium aphanidermatum and Rhizoctonia solani causes severe damage to plants, such as cucumber. This soil-borne infectious disease was not controlled effectively by chemical pesticide. Since these diseases spread through the soil, chemical agents are usually ineffective. Instead, biological control, including antagonistic microbe can be used as a preferred control method. An efficient method was developed to select an antagonistic strain to be used as a biological control agent strain. In this new method, surface tension reduction potential of an isolate was included in the ‘decision factor’ in addition to the other factors, such as growth rate, and pathogen inhibition rate. Considering these 3 decision factors by a statistical method, an isolate from soil was selected and was identified as Bacillus sp. GB16. In the pot test, this strain showed the best performance among the isolated strains. The lowest disease incidence rate and fastest seed growth was observed when Bacillus sp. GB16 was used. Therefore this strain was considered as plant growth promoting rhizobacteria (PGPR). The action of surface tension reducing component was deduced as the enhancement of wetting, spreading, and residing of antagonistic strain in the rhizosphere. This result showed that new selection method was significantly effective in selecting the best antagonistic strain for biological control of soil-borne infectious plant pathogen. The antifungal substances against P. aphanidermatum and R. solani were partially purified from the culture filtrates of Bacillus sp. GB16. In this study, lipopeptide possessing antifungal activity was isolated from Bacillus sp. GB16 cultures by various purification procedures and was identified as a surfactin-like lipopeptide based on the Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), high performance liquid chromatography mass spectroscopy (HPLC-MS), and quadrupole time-of-flight (Q-TOF) ESI-MS/MS data. The lipopeptide, named GB16-BS, completely inhibited the growth of Pythium aphanidermatum, Rhizoctonia solani, Penicillium sp., and Botrytis cineria at concentrations of 10 and 50 mg/L, respectively. A novel method to prevent the foaming and to provide oxygen was developed. During the production of surface active agent, such as lipopeptide (surfactin), large amount of foam was produced by aeration. This resulted in the carryover of cells to the outside of the fermentor, which leads to the significant loss of cells. Instead of using cell-toxic antifoaming agents, low amount of hydrogen peroxide was added. Catalase produced by cells converted hydrogen peroxide into oxygen and water. Also addition of corn oil as an oxygen vector as well as antifoaming agent was attempted. In addition, Ca-stearate, a metal soap, was added to enhance the antifoam activity of com oil. These methods could prevent the foaming significantly and maintained high dissolved oxygen in spite of lower aeration and agitation. Using these methods, high cell density, could be achieved with increased lipopeptide productivity. In conclusion to produce an effective biological control agent for soil-borne infectious disease, following strategies were attempted i) effective screening of antagonist by including surface tension as an important decision factor ii) identification of antifungal compound produced from the isolated strain iii) novel oxygenation by $H_2O_2-catalase$ with vegetable oil for antifungal lipopeptide production.

• Journal of Ginseng Research
• /
• 제39권3호
• /
• pp.213-220
• /
• 2015

Background: Korean ginseng (Panax ginseng Meyer) is a perennial herb prone to various root diseases, with Phytophthora cactorum being considered one of the most dreaded pathogens. P. cactorum causes foliar blight and root rot. Although chemical pesticides are available for disease control, attention has been shifted to viable, eco-friendly, and cost-effective biological means such as plant growth-promoting rhizobacteria (PGPR) for control of diseases. Methods: Native Bacillus amyloliquefaciens strain HK34 was isolated from wild ginseng and assessed as a biological control agent for ginseng. Leaves from plants treated with HK34 were analyzed for induced systemic resistance (ISR) against P. cactorum in square plate assay. Treated plants were verified for differential expression of defense-related marker genes using quantitative reverse transcription polymerase chain reaction. Results: A total of 78 native rhizosphere bacilli from wild P. ginseng were isolated. One of the root-associated bacteria identified as B. amyloliquefaciens strain HK34 effectively induced resistance against P. cactorum when applied as soil drench once (99.1% disease control) and as a priming treatment two times in the early stages (83.9% disease control). A similar result was observed in the leaf samples of plants under field conditions, where the percentage of disease control was 85.6%. Significant upregulation of the genes PgPR10, PgPR5, and PgCAT in the leaves of plants treated with HK34 was observed against P. cactorum compared with untreated controls and only pathogen-treated plants. Conclusion: The results of this study indicate HK34 as a potential biocontrol agent eliciting ISR in ginseng against P. cactorum.

• Mycobiology
• /
• 제34권2호
• /
• pp.67-72
• /
• 2006

Efficacy of resistance induction by the bacterial isolates Pseudomonas putida (TRL2-3), Micrococcus luteus (TRK2-2) and Flexibacteraceae bacterium (MRL412), which were isolated from the rhizosphere of plants growing in Jeju Mountain, were tested in a greenhouse. The disease severity caused by Phytophthora infestans was effectively reduced in the potato plants pre-inoculated with bacterial isolates compared with those of the untreated control plants growing in a greenhouse. In order to estimate the level of protection by the bacterial isolates, Mancozeb WP (Diesen $M^{(R)}$, Kyong nong) and DL-3-amino butyric acid (BABA) were pre-treated, whereas Dimethomorph WP ($Forum^{(R)}$, Kyong nong) and phosphonic acid ($H_{3}PO_{3}$) were post-treated the challenge inoculation with the pathogen. Disease severities of chemical pre-treated as well as post-treated plants were reduced compare to those of the untreated. The disease reduction in the plants pre-treated with Mancozeb WP was the highest, whereas that of post-treated with Dimethomorph WP was the lowest. The yields of plants pre-inoculated with three bacterial isolates were greatly increased than those of control plants. These results suggest that biological control by bacterial isolates might be an alternative strategy against late blight disease in potato plants growing in greenhouse.

• 한국미생물·생명공학회지
• /
• 제40권1호
• /
• pp.30-38
• /
• 2012

두 종의 Bacillus와 한 종의 Pseudomonas로 구성된 컨소시엄 미생물제제를 고추 경작지에 첨가하였을 때 경작지 토양의 미생물 다양성 변화를 조사하기 위해 건전한 토양의 지표가 되는 질소순환관여 미생물과 근권토양 내 섬유소 분해기능, 인산가용화기능과 urea 가수분해기능을 가지는 기능성미생물의 활성과 밀도를 측정하였다. 고추 경작지 토양에 컨소시엄 PGPR 미생물인 B. subtilis AH18, B. licheniformis K11과 P. fluorescens 2112의 컨소시엄 미생물제제를 처리하여 토양미생물의 다양성에 변화를 측정하여 컨소시엄 미생물제제의 처리에 의한 근권토양 미생물의 다양성 변화와 고추의 생육에 미치는 영향을 분석하였다. 컨소시엄 미생물제제 처리구의 경우 Actinomyces spp., Trichoderma spp., 광합성세균과 Azotobacter spp.가 다른 처리구에 비하여 1.7-5배 이상 높았으며, 질소 순환에 관여하는 미생물은 1.4-4배 증가되었다. 또한 기능성 미생물의 다양성도 화학제제나 물처리구와 비교하였을 때 1.3-3배 증가하였다. 건고추 수확량은 컨소시엄 미생물제제를 처리하였을 경우 대조구나 화학제제를 처리하였을 때보다 15%이상 수확량이 증대되었다. 따라서 PGPR 컨소시엄 미생물제제의 처리로 인해 고추 경작지 토양의 근권미생물 다양성과 작물의 생산성에 긍정적인 영향을 주는 것으로 생각된다. 추후 메타지노믹스를 활용하여 미생물 다양성 변화를 추가적으로 확인할 예정이다.