• 한국동물학회:학술대회논문집
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• 한국동물학회 2000년도 한국생물과학협회 학술발표대회
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• pp.129.2-130
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• 2000

No Abstract, See Full Text

• 미생물학회지
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• 제37권4호
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• pp.265-272
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• 2001

깨끗한 대기가 유지되는 청정지역 및 산성강하물의 영향을 받는 공단지역에서 자라는 떡갈나무(Quercus dentate Thunb.) 잎표면에서 분리한 내산성세균 배양으로부터 16S rDNA를 추출하여 모두 444개의 clone을 얻었으며, 이를 대상으로 Restriction fragment length polymorphism (RFLP)을 실시한 결과 총 17종류의 계통형 (phylotype)이 나타났다. 두 지역에서 나타난 대표적인 내산성 잎권세균 군집은 매우 단순하여 ${\gamma}$-Proteobacteria와 low-G+C gram-positive bacteria의 2개 group이었다. 식물 잎의 나이가 들수록 내산성 잎권세균 계통형의 다양성은 현저하게 증가하였다. 내산성 잎권세균 군집 구조는 $\gamma$-Proteobacteria에 속하는 Pseudomonas group과 Enterobacteriaceae, 그리고 low-G+C gram-positive bacteria 즉 Bacillus/Clostridium group에 속하는 Streptococcaceae와 Staphylococcus group이 우점하였다. 산성강하물에 따른 내산성 잎권세균 군집 구조의 변화는 상위 계통분류군(subphylum 수준)에서는 뚜렷이 볼 수 없었지만 보다 하위분류군에서 볼 때 $\gamma$-Proteobacteria의 Xanthomonadales group은 공단지역에서만, 그리고 $\alpha$-Proteobacteria의 Acetobacteraceae는 청정지역에서만 각각 검출되었으므로 이들 세균집단을 산성강서만, 그리고 $\alpha$-Proteobacteria의 Acetobacteraceae는 청정지역에서만 각각 검출되었으므로 이들 세균집단을 산성강 하물에 대한 지표세균으로서 사용할 수 있는 가능성을 남겨 놓았다.

• 미생물학회지
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• 제37권1호
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• pp.61-65
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• 2001

식물잎권의 잎표면세균에 대한 직접관찰과 이들을 분리시킨 용액 내 세균에 대한 간접관찰을 위하여 형광염료인 4', 6-diamidino-2-phenylindole(DAPI)와 acridine orange(AO)로 염색한 후 형광현미경을 사용하였다. AO로 염색한 잎표면은 배경형광이 진한 주홍색 이나 적색을 띠어 잎표면세균의 관잘 및 계수가 극히 힘들었으나 DAPI로 염색된 잎권세균은 뚜렷한 형광 영상을 나타내었다. 반면 잎표면세균 분리용액의 여과지에 대한 형광염색 결과는 DAPI와 AO 모두가 관찰이 가능하였다. 다만 DAPI가 AO에 비하여 형광 영상이 좀 더 뚜렷하였고 AO 염색과정에서는 염색된 여과지에 대한 세척과정이 필수적이었다. 최적의 DAPI 염색법은 잎과 여과지 모두가 5 $\mu$g/ml의 농도에서 5분 동안 염색하는 것이었다. 잎권의 형광현미경 관찰에 있어서 핵심적인 요소는 잎에서 나오는 수분을 최소화하는 것으로서 염색된 잎 시료를 거름종이 위에 올려놓고 공기 중에서 말리는 대신 $70^{\circ}C$를 유지한 건조기에서 2분 동안 말린 다음 바로 현미경으로 관찰하는 것이 가장 종은 방법인 것으로 확인되었다. 이렇게 확립된 형광현미경 관찰법을 떡갈나무의 잎권세균을 성공적으로 관찰하고 계수할 수 있었다.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2002년도 추계학술대회
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• pp.100-105
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• 2002

The diversity of epiphytic bacterial communities on deciduous oak tree (Quercus dentate Thunb.) leaves was examined both in the natural forest area with a clean air and in the industrial estate to assess effects of acidic deposition to the phyllosphere using 16S rDNA sequence data. In addition, acid-tolerant epiphytic bacterial communities were compared. A total of 78 epiphytic and 444 acid-tolerant clones were obtained from clone libraries, resulting in 20 and 17 phylotypes by analysis of restriction fragment length polymorphism (RFLP) for PCR-amplified 16S rDNA products. A low bacterial diversity in both areas was found. As tree leaves grow older, bacterial diversities were slightly increased in the level of subphylum. The community structure of epiphytic bacteria in both areas in April consisted of only two subphyla, $\beta-and\;\gamma-Proteobacteria$. In August two additional subphyla in both areas were found, but the composition was a little different, Acidobacteria and Cytophaga-Flexibacter-Bacteroids (CFB) group in the industrial estate and a -Proteobacteria and CFB group in the natural area, respectively. Acidobacteria could be an indicator of epiphytic bacteria for acidic deposition on plant leaves, whereas a -Proteobacteria be one of epiphytic bacteria that naturally survive on leaves that are not affected by acidic deposition. The acid-tolerant bacterial communities in April were composed of two subphyla, $\gamma-Proteobacteria$ and Low G+C gram-positive bacteria in both areas, and in August a-Proteobacteria was added to the community just in the natural forest area. The direct influence of acidic deposition on the acid-tolerant bacterial phylogenetic composition could not be detected in higher taxonomic levels such as subphylum, but at narrower or finer levels it could be observed by a detection of Xanthomonadales group of $\gamma-Proteobacteria$ just in the industrial estate.

• 미생물학회지
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• 제33권4호
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• pp.262-266
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• 1997

산성강하물의 영향을 받는 대전공단지역과 영향을 받지 않는 청정지역인 대전 계족산 자연휴양림에서 자라는 밤나무(Castanea crenata)의 잎표면에서 서식하는 총세균수, 생존세균수, 종속영양세균수, 내산성세균수를 1996년 8월부터 1997년 8월까지 5회에 걸쳐 조사하였다. 공단지역 잎표면 평균 총세균수, 생존세균수 및 종속영양세균수는 각각 $9.9{\times}10^5cell/cm^2$, $1.6{\times}10^6cell/cm^2$, $7.1{\times}10^3cfu/cm^2$로서 청정지역에 비하여 각각 1.5배, 2배, 2.6배 정도로 관찰되었다. MPN법으로 측정한 pH 5.6에서의 잎표면 내산성세균수는 공단지역 $3.3{\times}10^4$, 청정지역 $3.4{\times}10^4MPN/cm^2$로 거의 같았고, pH 4.0에서의 내산성세균수는 공단지역에서 $1.9{\times}10^{-1}MPN/cm^2$인 반면 청정지역세서는 전혀 검출되지 않았다. pH 3.0에서의 내산성 잎표면세균수는 공단지역과 청정지역의 잎권 어느 곳에서도 검출되지 않았다. 한편 계절별 잎포면세균수의 분포는 대체로 잎이 나기 시작하여 크기가 가장 작은 5월에 최대를, 그리고 낙엽이 지는 11월에 최소를 나타내었다. 이런 결과는 공단지역의 대기오염물질의 침적이 주변의 식물 잎표면 세균수를 감소시키지는 않으며, 특히 산성강하물의 영향으로 내산성세균수가 증가함을 보여주고 있다.

• Journal of Microbiology and Biotechnology
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• 제16권10호
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• pp.1622-1628
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• 2006

Bacteria from the Methylobacterium genus, called pink-pigmented facultative methylotrophic bacteria (PPFMs), are common inhabitants of plants, potentially dominating the phyllosphere population, and are also encountered in the rhizosphere, seeds, and other parts of plants, being versatile in nature. The consistent success of the Methylobacterium plant association relies on methylotrophy, the ability to utilize the one-carbon compound methanol emitted by plants. However, the efficiency of Methylobacterium in plant growth promotion could be better exploited and thus has attracted increasing interest in recent years. Accordingly, the present study investigated the inoculation effects of Methylobacterium sp. strains CBMB20 and CBMB 110 on seed imbibition to tomato and red pepper on the growth and accumulation of phytohormone levels under gnotobiotic conditions. Seeds treated with the Methylobacterium strains showed a significant increase in root length when compared with either the uninoculated control or Methylobacterium extorquens $miaA^-$ knockout mutanttreated seeds. Extracts of the plant samples were used for indole-3-acetic acid (IAA), trans-zeatin riboside (t-ZR), and dihydrozeatin riboside (DHZR) assays by immunoanalysis. The treatment with Methylobacterium sp. CBMB20 or CBMB 110 produced significant increases in the accumulation of IAA and the cytokinins t-ZR and DHZR in the red pepper extracts, whereas no IAA was detected in the tomato extracts, although the cytokinin concentrations were significantly increased. Therefore, this study proved that the versatility of Methylobacterium as a plant-growth promoting bacteria could be better exploited.

• Journal of Microbiology and Biotechnology
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• 제17권2호
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• pp.226-233
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• 2007

Members of Methylobacterium, referred as pink-pigmented facultative methylotrophic bacteria, are frequently associated with terrestrial and aquatic plants, tending to form aggregates on the phyllosphere. We report here that the production of autoinducer molecules involved in the cell-to-cell signaling process, which is known as quorum sensing, is common among Methylobacterium species. Several strains of Methylobacterium were tested for their ability to produce N-acyl-homoserine lactone (AHL) signal molecules using different indicators. Most strains of Methylobacterium tested could elicit a positive response in Agrobacterium tumefaciens harboring lacZ fused to a gene that is regulated by autoinduction. The synthesis of these compounds was cell-density dependent, and the maximal activity was reached during the late exponential to stationary phases. The bacterial extracts were separated by thin-layer chromatography and bioassayed with A. tumefaciens NTI (traR, tra::lacZ749). They revealed the production of various patterns of the signal molecules, which are strain dependent. At least two signal molecules could be detected in most of the strains tested, and comparison of their relative mobilities suggested that they are homologs of N-octanoyl-$_{DL}$-homoserine lactone ($C_8-HSL$) and N-decanoyl-$_{DL}$-homoserine lactone ($C_{10}-HSL$).

• 한국미생물·생명공학회지
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• 제47권1호
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• pp.1-10
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• 2019

Saline soils comprise more than half a billion hectares worldwide. Thus, they warrant attention for their efficient, economical, and environmentally acceptable management. Halophytes are being progressively utilized for human benefits. The halophyte microbiome contributes significantly to plant performance and can provide information regarding complex ecological processes involved in the osmoregulation of halophytes. Microbial communities associated with the rhizosphere, phyllosphere, and endosphere of halophytes play an important role in plant health and productivity. Members of the plant microbiome belonging to domains Archaea, Bacteria, and kingdom Fungi are involved in the osmoregulation of halophytes. Halophilic microorganisms principally use compatible solutes, such as glycine, betaine, proline, trehalose, ectoine, and glutamic acid, to survive under salinity stress conditions. Plant growth-promoting rhizobacteria (PGPR) enhance plant growth and help to elucidate tolerance to salinity. Detailed studies of the metabolic pathways of plants have shown that plant growth-promoting rhizobacteria contribute to plant tolerance by affecting the signaling network of plants. Phytohormones (indole-3-acetic acid and cytokinin), 1-aminocyclopropane-1-carboxylic acid deaminase biosynthesis, exopolysaccharides, halocins, and volatile organic compounds function as signaling molecules for plants to elicit salinity stress. This review focuses on the functions of plant microbiome and on understanding how the microorganisms affect halophyte health and growth.

• 식물병연구
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• 제22권2호
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• pp.81-93
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• 2016

식물생장촉진세균은 식물의 생장과 수확량을 촉진하고, 식물병에 대한 유도저항성을 유도하는 것으로 보고되었다. 본 논문에서 연구의 목적은 가로수와 고추의 엽면에 엽권정착 식물생장촉진세균을 처리하여, 식물생장촉진세균의 적용 범위를 확장하였다. 수목의 엽권에서 내생포자 형성 세균 1,056개 균주를 분리하여, protease, chitinase, lipase를 포함한 효소활성과 진균병인 C. graminicola와 B. cinerea에 대한 길항작용을 측정하였다. 1차 선발된 bacilli 14개 균주를 고추의 잎에 살포하여 엽권정착능을 시험하였다. 5B6, 8D4, 8G12 단독처리와 그 혼합처리군을 고추 엽면에 살포하여 생장촉진, 수확량증진, 병방제 효과를 고추 포장에서 관찰하였다. 대량배양을 통하여 선발된 균주를 대한민국 대전광역시 유성구 일대의 가로수에 살포하였을 때, 대조군과 비교하여 엽록소함량과 잎 두께가 증가하였다. 선발된 3개 균주를 수목에 엽면살포했을 때, 벚나무 진균성갈색무늬구멍병을 저해하였고 은행나무의 낙엽생성을 촉진하였다. 종합적으로 본 연구는 엽권정착세균의 엽면살포를 통하여 가로수와 고추의 생장을 촉진시키고, 식물병을 방제하는 엽권정착세균의 적용 가능성을 제시한다.

• Journal of Microbiology and Biotechnology
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• 제28권2호
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• pp.227-235
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• 2018

Foodborne illness represents a major threat to public health and is frequently attributed to pathogenic microorganisms on fresh produce. Recurrent outbreaks often come from vegetables that are grown close to or within the ground. Therefore, the first step to understanding the public health risk of microorganisms on fresh vegetables is to identify and describe microbial communities. We investigated the phyllospheres on Chinese cabbage (Brassica rapa subsp. pekinensis, N = 54). 16S rRNA gene amplicon sequencing targeting the V5-V6 region of 16S rRNA genes was conducted by employing the Illumina MiSeq system. Sequence quality was assessed, and phylogenetic assessments were performed using the RDP classifier implemented in QIIME with a bootstrap cutoff of 80%. Principal coordinate analysis was performed using a weighted Fast UniFrac matrix. The average number of sequence reads generated per sample was 34,584. At the phylum level, bacterial communities were composed primarily of Proteobacteria and Bacteroidetes. The most abundant genera on Chinese cabbages were Chryseobacterium, Aurantimonadaceae_g, Sphingomonas, and Pseudomonas. Diverse potential pathogens, such as Pantoea, Erwinia, Klebsiella, Yersinia, Bacillus, Staphylococcus, Salmonella, and Clostridium were also detected from the samples. Although further epidemiological studies will be required to determine whether the detected potential pathogens are associated with foodborne illness, our results imply that a metagenomic approach can be used to detect pathogenic bacteria on fresh vegetables.