• 한국토양비료학회지
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• 제20권2호
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• pp.179-183
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• 1987

고추, 마늘, 화훼, 배추및 양파등(等)의 연작지(連作地) 토양(土壤)을 공시(供試)하여 세균(細菌), 사상균(絲狀菌) 및 이들 미생물(微生物)의 분포비율등(分布比率等)을 조사(調査)하기 위하여 실내시험(室內試驗)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 고추및 마늘 연작지토양(連作地土壤)의 세균(細菌) 및 사상균수(絲狀菌數)는 일반답토양(一般畓土壤)에 비(比)하여 현저(顯著)히 적었다. 2. 연작지토양중(連作地土壤中) 세균(細菌)은 당류(糖類)를 산화(酸化)하여 생육(生育)하는 당류자화성세균(糖類自化性細菌)과 질산환원(窒酸還元)을 가진 세균수(細菌數)가 많았다. 3. 마늘과 토마토 연작지토양중(連作地土壤中)에는 당(糖)의 산화작용(酸化作用)에 의한 Alkali 생성균수(生成菌數)가 많았다. 4. 작물연작지토양(作物連作地土壤)의 근권(根圈)에서는 대체(大體)로 Pseudomonas, Xanthomonas, Bacillus, Achromobacter 속(屬)의 세균(細菌)이 그리고 사상균(絲狀菌)은 Penicillium속(屬)이 가장 많았으며, 다음은 Phoma, Humicola 및 Aspergillus속(屬)의 균주(菌株)였다. 5. 전공시토양(全供試土壤)에서 식물독소생성균(植物毒素生成菌)인 Stachybotris속(屬)의 사상균(絲狀菌)이 분리(分離)되었다.

• 미생물학회지
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• 제51권4호
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• pp.347-354
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• 2015

콩은 우리나라와 극동아시아가 원산지로 알려져 있으나 국산 콩의 근권 세균 군집에 대한 연구는 미흡하다. 따라서 본 연구에서는 국산 재배콩을 대상으로 차세대 염기서열 분석 방법인 파이로시퀀싱 방법을 사용하여 콩 근권 세균 군집 구조를 해석하고 생육단계별 군집의 변화 및 콩 근권의 핵심 세균 군집을 구명하고자 하였다. 세균 군집 분석 결과, 근권 세균의 군집은 근권과 비근권간에 뚜렷한 차이를 보였으며, 총 21개의 문으로 구성되었다. Proteobacteria가 가장 우점(36.6-42.5%)하였고, Acidobacteria (8.6-9.4%), Bacteroidetes (6.1-10.9%), Actinobacteria (6.4-9.8%), Firmicutes (5.7-6.3%) 등의 순으로 상대풍부도가 감소하였다. 모든 생육단계에 걸쳐 콩 근권의 핵심 세균 군집에는 Proteobacteria에 속한 OTU들이 가장 많이 분포하였으며, 이들 중 Bradyrhizobium에 속한 OTU의 상대 풍부도가 가장 높았다. 본 연구결과는 콩 근권의 핵심 세균 군집은 주로 생육 촉진 기능과 유기물 순환에 관련된 OTU로 구성되어 있다는 것을 보여주었다.

• The Plant Pathology Journal
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• 제37권6호
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• pp.662-672
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• 2021

Plant growth-promoting bacteria improve plant growth under abiotic stress conditions. However, their effects on microbial succession in the rhizosphere are poorly understood. In this study, the inoculants of Bacillus mesonae strain H20-5 were administered to tomato plants grown in soils with different salinity levels (EC of 2, 4, and 6 dS/m). The bacterial communities in the bulk and rhizosphere soils were examined 14 days after H20-5 treatment using Illumina MiSeq sequencing of the bacterial 16S rRNA gene. Although the abundance of H20-5 rapidly decreased in the bulk and rhizosphere soils, a shift in the bacterial community was observed following H20-5 treatment. The variation in bacterial communities due to H20-5 treatment was higher in the rhizosphere than in the bulk soils. Additionally, the bacterial species richness and diversity were greater in the H20-5 treated rhizosphere than in the control. The composition and structure of the bacterial communities varied with soil salinity levels, and those in the H20-5 treated rhizosphere soil were clustered. The members of Actinobacteria genera, including Kineosporia, Virgisporangium, Actinoplanes, Gaiella, Blastococcus, and Solirubrobacter, were enriched in the H20-5 treated rhizosphere soils. The microbial co-occurrence network of the bacterial community in the H20-5 treated rhizosphere soils had more modules and keystone taxa compared to the control. These findings revealed that the strain H20-5 induced systemic tolerance in tomato plants and influenced the diversity, composition, structure, and network of bacterial communities. The bacterial community in the H20-5 treated rhizosphere soils also appeared to be relatively stable to soil salinity changes.

• International Journal of Industrial Entomology and Biomaterials
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• 제35권2호
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• pp.63-70
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• 2017

Native fluorescent pseudomonas bacteria were isolated from rhizosphere soil of mulberry and were evaluated against powdery mildew. In vitro conidial germination study showed significant (P<0.05) variation in conidial germination by bacterial strains Pf1 and Pf3. Mildew incidence was significantly varied due to treatment with various pseudomonas strains in vivo. Significantly (P<0.05) less mildew incidence was in plants treated with the bacterial strain Pf1 (9.11%) followed by Pf3 (13.48%) controlling 69.40% and 54.75% respectively compared with untreated control. Similarly, mildew severity was least (8.51%) in plants treated with strain Pf1 followed by Pf5 (9.23%) and Pf3 (9.72%) controlling the severity by 84.51%, 77.01% and 71.96% respectively compared with control. The bacterial strains significantly influenced biochemical constituents such as chlorophyll, protein and soluble sugar content of the mulberry leaf. Similarly, bacterial strains significantly increased the activity of the peroxidase (PO) and Polyphenol oxydase (PPO) activity from $7^{th}$ day up to the $28^{th}$ day after treatment. The strain Pf1, Pf3 and Pf5 exhibited a marked enhancement in the peroxidase at different periods of infection. Significant (P<0.01) negative correlation was found between powdery mildew severity with phenol content ($R^2=0.67$) as well as peroxidase ($R^2=0.92$) and polyphenol oxidase ($R^2=0.72$) activity thus confirms induction of systemic resistance in mulberry by pseudomonas bacteria. The study shows scope for exploration of rhizosphere fluorescent pseudomonas bacteria for induction of systemic resistance in mulberry to contain powdery mildew disease effectively.

• Journal of Microbiology and Biotechnology
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• 제22권6호
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• pp.763-770
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• 2012

Pseudomonas fluorescens 2112, isolated in Korea as an indigenous antagonistic bacteria, can produce 2,4-diacetylphloroglucinol (2,4-DAPG) and the siderophore pyoveridin2112 for the control of phytophthora blight of red-pepper. P. fluorescens 2112 was classified into a new genotype C among the 17 genotypes of 2,4-DAPG producers, by phlD restriction fragment length polymorphism (RFLP). The colonizing ability of P. fluorescens 2112 in pea rhizosphere was equal to the well-known pea colonizers, P. fluorescens Q8r1 (genotype D) and MVP1-4 (genotype P), after 6 cycling cultivations for 18 weeks. Four tested 2,4-DAPG-producing Pseudomonas spp. could colonize with about a 96% dominance ratio against total bacteria in pea rhizosphere. The strain P. fluorescens 2112 was as good a colonizer as other Pseudomonas spp. genotypes in pea plant growth-promoting rhizobacteria.

• 한국미생물·생명공학회지
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• 제34권1호
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• pp.78-82
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• 2006

Since there could be more and rather various diazotrophs in rhizosphere of wild crops than those in rhizosphere of cultivars, some wild gramineous crops grown in Korea were collected for isolating nitrogen-fixing bacteria. Six diazotrophs were purified from their roots using nitrogen-free media. The isolated bacteria were partially identified as 4 genera by 16S rDNA sequence analysis: Stenotrophomonas sp., Bosea sp., Klebsiella sp., and Azorhizobium sp. By PCR amplification and sequence analysis, DNA fragments extracted from all isolates turned out to have an individual nifH homologous gene. Five isolates (KNUC163, KNUC165, KNUC169, KNUC170, and KNUC171) showed auxin activity and four isolates (KNUC163, KNUC166, KNUC170, and KNUC171) produced siderophores. Especially,3 strains of S. maltophilia showed both auxin and siderophore activities. In conclusion, the isolated nitrogen-fixing bacteria might have capabilities for plant growth promotion.

• 미생물학회지
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• 제49권3호
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• pp.297-300
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• 2013

인삼근계(근권, 근면, 근내부) 내 EPS 생성세균의 밀도를 측정한 결과, 근권토양 내에는 $2.4{\times}10^6$ CFU/g, 근면에는 $9.1{\times}10^6$ CFU/g, 그리고 근내부에는 $2.0{\times}10^4$ CFU/g로 확인되어 다수의 EPS 생성세균이 분포하고 있음이 확인되었다. 인삼 근계로부터 EPS 생성 우수 균주 24균주를 순수분리하고 계통학적 특성을 확인한 결과, 근권(RS)으로부터 분리된 EPS 생성세균은 Arthrobacter 속 6균주, 그리고 Rhizobium 속 1균주로 나타났다. 근면(RP)으로 부터 분리된 EPS 생성세균은 Arthrobacter 속 6균주, Rhodococcus 속 1균주, Pseudomonas 속 1균주로 나타났다. 근내부(IR)에서 분리된 EPS 생성세균은 Rhizobium 속 6균주, Bacillus 속 1균주 그리고 Rhodococcus 속 1균주, Pseudomonas 속 1균주로 나타났다. 근권과 근면에서 분리된 EPS 세균 중 Arthrobacter 속에 속하는 균주는 가장 특징적인 세균으로 밝혀졌으며, Rhizobium 속은 근내부에서 분리된 가장 특징적인 EPS 생성세균으로 나타났다. EPS 생성 우수균주 Rhizobium sp. 1NP2 (KACC 17637)는 10 g/L 그리고 Arthrobacter sp. 5MP1 (KACC 17636)는 4.9 g/L의 다당을 생성하였으며, 당단백질의 구성당 성분을 확인한 결과, galactose, glucose, mannose를 구성하고 있었으며, glucosamine의 아미노당이 나타났다. 특히, glucose는 72.7-84.9%로 주요 구성당임이 확인되었다.

• Journal of Ginseng Research
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• 제40권2호
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• pp.97-104
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• 2016

Background: Rhizobacteria play an important role in plant defense and could be promising sources of biocontrol agents. This study aimed to screen antagonistic bacteria and develop a biocontrol system for root rot complex of Panax notoginseng. Methods: Pure-culture methods were used to isolate bacteria from the rhizosphere soil of notoginseng plants. The identification of isolates was based on the analysis of 16S ribosomal RNA (rRNA) sequences. Results: A total of 279 bacteria were obtained from rhizosphere soils of healthy and root-rot notoginseng plants, and uncultivated soil. Among all the isolates, 88 showed antagonistic activity to at least one of three phytopathogenic fungi, Fusarium oxysporum, Fusarium solani, and Phoma herbarum mainly causing root rot disease of P. notoginseng. Based on the 16S rRNA sequencing, the antagonistic bacteria were characterized into four clusters, Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetesi. The genus Bacillus was the most frequently isolated, and Bacillus siamensis (Hs02), Bacillus atrophaeus (Hs09) showed strong antagonistic activity to the three pathogens. The distribution pattern differed in soil types, genera Achromobacter, Acidovorax, Brevibacterium, Brevundimonas, Flavimonas, and Streptomyces were only found in rhizosphere of healthy plants, while Delftia, Leclercia, Brevibacillus, Microbacterium, Pantoea, Rhizobium, and Stenotrophomonas only exist in soil of diseased plant, and Acinetobacter only exist in uncultivated soil. Conclusion: The results suggest that diverse bacteria exist in the P. notoginseng rhizosphere soil, with differences in community in the same field, and antagonistic isolates may be good potential biological control agent for the notoginseng root-rot diseases caused by F. oxysporum, Fusarium solani, and Panax herbarum.

• The Plant Pathology Journal
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• 제27권3호
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• pp.242-248
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• 2011

Several soil bacteria were found to degrade N-Acylhomoserine lactones (NAHLs), thereby interfering with the bacterial quorum sensing system. In this research, fifteen strains of NAHL degrading rhizobacteria were isolated from potato rhizosphere. Based on phenotypic characteristics and 16S rDNA sequence analyses, the strains were identified as members of genera Bacillus, Streptomyces, Arthrobacter, Pseudomonas and Mesorhizobium. All tested isolates were capable to degrade both synthetic and natural NAHL produced by Pectobacterium carotovorum subsp. carotovorum (Pcc) strain EMPCC. In quorum quenching experiments selected isolates, especially Mesorhizobium sp., were markedly reduced the pathogenicity of Pcc strain EMPCC in potato tubers and totally suppressed tissue maceration on potato tubers. These led to consider the latter as a useful biocontrol agent against Pectobacterium spp.

• 한국미생물·생명공학회지
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• 제33권3호
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• pp.169-177
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• 2005

본 연구는 어업이나 농업 등의 인간활동에 의하여 상당한 영향을 받고 있는 순천만 갈대의 근권에서 이루어지는 정화작용에 있어 미생물의 역할을 조사하는 것에 중점을 두었다. 일반적으로 만은 환경 스트레스로 인한 갑작스런 충격을 감소시키는 완충지역으로서의 역할을 하는 것으로 알려져 있다. 갈대근권에서 이루어지는 정화기능에 있어 미생물의 역할을 밝히기 위한 첫 번째 노력의 일환으로 벤젠, 톨루엔, 또는 자일렌이 단일 탄소 및 에너지원으로 첨가된 농화배양법을 사용하여 BTEX를 분해할 수 있는 두 종류의 그람양성 세균을 순수분리하였다. 다양한 온도조건의 BTEX배지에서 이들 세균을 배양하는 동안 BTEX의 분해율 및 성장률을 주기적으로 조사한 결과 $37^{\circ}C$에서 가장 빠른 기질 분해율을 보였고 $42^{\circ}C$의 고온에서도 두 균 모두 잘 성장하는 것으로 나타났다. 본 연구에서 시험한 수은, 카드뮴, 납, 바륨, 철 대부분의 중금속에 강한 내성뿐만 아니라 ampicillin을 비롯한 시험한 5종류의 항생제 모두에 강한 내성을 나타냈다. 16S rRNA 유전자 서열과 다양한 표현형 및 형태학적 특성을 기초로 한 동정의 결과 BTEX를 분해할 수 있는 두 균주는 $95{\%}$상의 신뢰도로 Microbacterium sp.와 Rhodococcus sp.로 나타났고, 각 균주는 Microbacterium sp. EMB-1과 Rhodococcus sp. EMB-2로 명명하였다. 이러한 결과는 주요한 염습지 식물중의 하나인 갈대의 근권에서 살아가는 이들 균주들이 BTEX와 같은 석유로 오염된 근권 환경의 정화작용에 중요한 역할을 할 수 있음을 제시해주었다.