• 환경생물
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• 제26권1호
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• pp.42-46
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• 2008

Brassica rapa subsp. pekinensis (배추) 근권에 서식하는 종속영양세균의 군집 밀도 및 군집수준 생리활성을 2곳의 지역에서 각각 측정하였다. 근권의 종속영양세균군집 평균 밀도는 수원이 $2.65\times10^6CFU\;g^{-1}$ soil, 예산이 $3.75\times10^6CFU\;g^{-1}$ soil로 나타났고, 토양은 수원이 $2.45\times10^6CFU\;g^{-1}$ soil, 예산이 $2.97\times10^6CFU\;g^{-1}$ soil로 각각 나타났다. 평균 기능풍부도(functional richness)는 수원이 90.8, 예산이 154.1로 각각 나타났다. 군집 밀도와 기능 풍부도 사이에는 밀접한 상관관계가 보였다. 양쪽 근권에서 가장 활발하게 분해된 기질은 adonitol, L-asparagine, D-gluconic acid, L-glutamic acid와 D-galacturonic acid 등이었으나, 수원과 예산 근권에서의 기질 분해 양상은 뚜렷한 차이를 보였다. 한편 두 곳의 토양 역시 어느 정도 차이를 보였으나, D-raffinose 및 D-mannose는 공통적으로 잘 분해되는 기질로 나타났다.

• 미생물학회지
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• 제50권1호
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• pp.40-45
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• 2014

전 세계적으로 친환경 농업을 위해 식물생장촉진 근권세균을 이용한 미생물 비료에 대한 관심이 증가하고 있는데 투여하는 세균을 식물 근권에 보다 장기간 잔류시키기 위해 식물생장 촉진능이 있는 균주를 alginate bead에 고정화하여 식물생장을 조사하였다. 발아된 토마토 유묘에 Arthrobacter woluwensis ED를 $1{\times}10^6$ cells/g 로 처리하고 30일 재배 후 자라난 토마토의 shoot와 뿌리 길이 및 습윤과 건조중량을 측정한 결과 비접종 대조군과 비교하여 균주 현탁액 접종군은 각각 36.2, 59.0, 51.1과 37.5%씩 유의성 있게 증가하였으며 고정화 균주 접종군은 각각 42.0, 67.4, 62.5와 60.4%씩 유의성 있게 증가하였다. 고정화 균주 접종군은 균주 현탁액 접종군에 비하여 각각 6, 8, 11과 23% 증가하였다. 접종 균주가 식물 근권에서 유지되는 양상을 관찰하기 위해 denaturing gradient gel electrophoresis를 이용하여 토양세균 군집을 분석하였는데 균주 현탁액 접종군에서 ED 균주의 DNA band intensity는 접종일로부터 1주일까지 가장 높게 나타났으나 그 이후로 감소하여 접종 2주 후 비접종 대조군과 비슷한 band intensity를 나타내었다. 반면, 고정화 균주 접종군의 ED 균주 band intensity는 접종일로부터 초기에는 비접종 대조군과 비슷하였으나 이후 급격하게 증가하여 계속 높게 유지되어 3주까지 band intensity가 현탁액 접종군 보다 높았다. 따라서 alginate에 A. woluwensis ED를 고정하여 적용하는 방법이 현탁액 적용보다 식물 근권에 균주의 공급을 효과적으로 유지하면서 식물생장을 더욱 촉진하는 것으로 나타났다.

• 한국토양비료학회지
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• 제20권1호
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• pp.69-76
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• 1987

The aerobic heterotrophic bacteria in the histosphere associated with grasses (Gramineae, Caryphyllaceae, Crucifereae) and rice cultivars in saline and reclaimed saline paddy soils were varied with species and rice cultivars. The fraction of aerobic heterotrophic $N_2$-fixing bacteria to the total aerobic heterotrophic bacteria were averaged to eighteen percent in the histosphere of grasses and rice. Acetylene reducing activity of these bacteria were ranged from 1 to 24 n mole/tube/hr. Most of the bacteria strains were predominated of hydrogen utilizing bacteria. The majority of these bacteria were closed to Pseudomonas, Azospirillum, Klebsiella and Agrobacter.

• The Plant Pathology Journal
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• 제38권6호
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• pp.583-592
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• 2022

Root-knot nematode disease is a widespread and catastrophic disease of tobacco. However, little is known about the relationship between rhizosphere bacterial community and root-knot nematode disease. This study used 16S rRNA gene sequencing and PICRUSt to assess bacterial community structure and function changes in rhizosphere soil from Meloidogyne incognita-infected tobacco plants. We studied the rhizosphere bacterial community structure of M. incognita-infected and uninfected tobacco plants through a paired comparison design in two regions of tobacco planting area, Yuxi and Jiuxiang of Yunnan Province, southwest China. According to the findings, M. incognita infection can alter the bacterial population in the soil. Uninfested soil has more operational taxonomic unit numbers and richness than infested soil. Principal Coordinate Analysis revealed clear separations between bacterial communities from infested and uninfested soil, indicating that different infection conditions resulted in significantly different bacterial community structures in soils. Firmicutes was prevalent in infested soil, but Chloroflexi and Acidobacteria were prevalent in uninfested soil. Sphingomonas, Streptomyces, and Bradyrhizobium were the dominant bacteria genera, and their abundance were higher in infested soil. By PICRUSt analysis, some metabolism-related functions and signal transduction functions of the rhizosphere bacterial community in the M. incognita infection-tobacco plants had a higher relative abundance than those uninfected. As a result, rhizosphere soils from tobacco plants infected with M. incognita showed considerable bacterial community structure and function alterations.

• Journal of Microbiology and Biotechnology
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• 제26권3호
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• pp.549-557
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• 2016

Aphids are a large group of hemipteran pests that affect the physiology, growth, and development of plants by using piercing mouthparts to consume fluids from the host. Based an recent data, aphids modulate the microbiomes of plants and thereby affect the overall outcome of the biological interaction. However, in a few reports, aboveground aphids manipulate the metabolism of the host and facilitate infestations by rhizosphere bacteria (rhizobacteria). In this study, we evaluated whether aphids alter the plant resistance that is mediated by the bacterial community of the root system. The rhizobacteria were affected by aphid infestation of pepper, and a large population of gram-positive bacteria was detected. Notably, Paenibacillus spp. were the unique gram-positive bacteria to respond to changes induced by the aphids. Paenibacillus polymyxa E681 was used as a rhizobacterium model to assess the recruitment of bacteria to the rhizosphere by the phloem-sucking of aphids and to test the effect of P. polymyxa on the susceptibility of plants to aphids. The root exudates secreted from peppers infested with aphids increased the growth rate of P. polymyxa E681. The application of P. polymyxa E681 to pepper roots promoted the colonization of aphids within 2 days of inoculation. Collectively, our results suggest that aphid infestation modulated the root exudation, which led to the recruitment of rhizobacteria that manipulated the resistance of peppers to aphids. In this study, new information is provided on how the infestation of insects is facilitated through insect-derived modulation of plant resistance with the attraction of gram-positive rhizobacteria.

• Mycobiology
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• 제32권3호
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• pp.139-147
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• 2004

A severe damping-off disease of bush okra caused by Pythium aphanidermatum, was diagnosed in plastic houses in Der Attia village, 15 km southwest of El-Minia city, Egypt, during the winter of 2001. Bush okra seedlings showed low emergence with bare patches inside the plastic houses. Seedlings that escaped pre-emergence damping-off showed poor growth, stunting and eventually collapsed. Examination of the infected tissues confirmed only Pythium aphanidermatum, showing its typical intercalary antheridia, and lobulate zoosporangia. P. aphanidermatum was shown to be pathogenic on bush okra under pot and field experiments. Bacteria making inhibition zones against the damping-off fungus P. aphanidermatum were selected. Agar discs from rhizosphere soil of bush okra containing colonies were transferred onto agar plate culture of P. aphanidermatum. After 2 days of incubation, colonies producing clear zones of non-Pythium growth were readily detected. The two bacteria with the largest inhibition zones were identified as Pseudomonas fluorescens. Bush okra emergence(%) in both pot and plastic houses experiments indicated that disease control could be obtained by applying P. fluorescens to the soil or coating the bacteria to the bush okra seeds before sowing. In the plastic houses, application of the bacteria onto Pythium-infested soil and sowing bush okra seeds dressed with bacteria gave 100% emergence. In addition, This was the first reported disease of bush okra by this oomycete in Egypt.

• 한국미생물학회:학술대회논문집
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• 한국미생물학회 2005년도 International Meeting of the Microbiological Society of Korea
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• pp.201.2-201
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• 2005

• 한국식물병리학회:학술대회논문집
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• 한국식물병리학회 1999년도 임시총회 및 추계 학술발표회
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• pp.66.2-66
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• 1999

• Journal of Microbiology and Biotechnology
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• 제20권5호
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• pp.862-870
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• 2010

Cyperus rotundus L. is a perennial herb that was found to be dominating an area in northeast Brazil previously contaminated with petroleum. In order to increase our knowledge of microorganism-plant interactions in phytoremediation, the bacterial community present in the rhizosphere and roots of C. rotundus was evaluated by culture-dependent and molecular approaches. PCR-DGGE analysis based on the 16S rRNA gene showed that the bacterial community in bulk soil, rhizosphere, and root samples had a high degree of similarity. A complex population of alkane-utilizing bacteria and a variable nitrogen-fixing population were observed via PCR-DGGE analysis of alkB and nifH genes, respectively. In addition, two clone libraries were generated from alkB fragments obtained by PCR of bulk and rhizosphere soil DNA samples. Statistical analyses of these libraries showed that the compositions of their respective populations were different in terms of alkB gene sequences. Using culturedependent techniques, 209 bacterial strains were isolated from the rhizosphere and rhizoplane/roots of C. rotundus. Dot-blot analysis showed that 17 strains contained both alkB and nifH gene sequences. Partial 16S rRNA gene sequencing revealed that these strains are affiliated with the genera Bosea, Cupriavidus, Enterobacter, Gordonia, Mycoplana, Pandoraea, Pseudomonas, Rhizobium, and Rhodococcus. These isolates can be considered to have great potential for the phytoremediation of soil with C. rotundus in this tropical soil area.

• Journal of Microbiology and Biotechnology
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• 제16권2호
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• pp.193-199
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• 2006

Halotolerant spore-forming Gram-positive bacteria were isolated from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides. The different isolates were characterized genetically using an amplified ribosomal DNA restriction analysis (ARDRA), and phenotypically based on their colonial morphology, physiology, and nutritional requirements. Three different 16S rRNA gene-based genotypes were observed at a 100% similarity using the enzymes HinfI, MspI, and RsaI, and the phenotypic results also followed the ARDRA groupings. Selected strains, representing the different ARDRA groups, were analyzed by 16S rDNA sequencing, and members of the genera Halobaeillus, Virgibacillus, and Oceanobacillus were found. Two isolates showed low 16S rDNA sequence similarities with the closest related species of Halobacillus, indicating the presence of new species among the isolates. The majority of the strains isolated in this study seemed to belong to the species O. iheyensis and were compared using an AP-PCR to determine whether they had a clonal origin or not. Different patterns allowed the grouping of the strains according to Pearson's coefficient, and the resulting dendrogram revealed the formation of two main clusters, denoted as A and B. All the strains isolated from the soil were grouped into cluster A, whereas cluster B was exclusively composed of the strains associated with the B. portulacoides roots. This is the first report on the isolation and characterization of halotolerant spore-forming Gram-positive bacteria that coexist with B. portulacoides. As such, these new strains may be a potential source for the discovery of bioactive compounds with industrial value.