• Korean Journal of Soil Science and Fertilizer
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• v.23 no.1
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• pp.60-66
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• 1990

Soybean [Glycin max (L.)] cv. Jangbaekkong was inoculated with 5 cultivated- and 5 uncultivated upland soils, in Yeongnam area, as soil inoculum and NifTAL peat inoculum as standard for soil inoculum potentials by Bradyrhizobium japonicum. 120 Bradyrhizobium japonicum isolates out of the soil populations were scored of three colony morphologies, designed "Dry", "Wet", and "Dry/Wet", and symbiotic effectiveness between "Dry" and "Wet" was compared. The results obtained were summarized as follows: 1. Indigenous populations of B. japonicum were above $10^4cells/g$. soil at the cultivated upland soils but were a few at the uncultivated upland soils except a colluvivum, orchard previously, in Yeongnam area. 2. Inoculum potentials of the cultivated upland soils were higher than the NifTAL inoculum and generally, nodule mass compensated nodule number for symbiotic effectiveness of soil populations. 3. Colony morphologies of soil populations showed the different proportions of "Dry" and "Wet" so that "Dry" types were dominant at the cultivated upland soils while "Wet" types at the uncultivated upland soils. 4. "Dry" colony morphology significantly exhibited higher symbiotic effectiveness than "Wet" types in nodule fresh weight, shoot dry weight, and shoot dry weight/nodule fresh weight. Therefore, as long as soil inoculum potentials, the growth of soybean at the cultivated upland soils could presumedly be affected by soil populations of Bradyrhizobium japonicum of "Dry" colony morphology.

• Proceedings of the Korean Society of Crop Science Conference
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• 1988.07a
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• pp.46-47
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• 1988

• Microbiology and Biotechnology Letters
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• v.34 no.1
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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.

• Microbiology and Biotechnology Letters
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• v.31 no.1
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• pp.18-24
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• 2003

For researching nitrogen-fixing bacteria associated with gramineous crops, we collected growing roots of rices, wheats, oats, barleys, ryes, and maizes at 19 sites of southern Korean peninsula. Endophytes and free living bacteria were isolated from those crop roots. Sixty-three isolates were classified on the basis of different morphology, size, color, host of colony, and the 16S rDNAs sequence. The analyses of PCR amplification for nifH gene and nitrogenase activity assay, revealed that all isolates contained nitrogen-fixing abilities. In addition, most of them have cellulase activity which is one of the common features of endophytic bacteria from plant.

• Proceedings of the Botanical Society of Korea Conference
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• 1987.07a
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• pp.81-101
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• 1987

In an attempt to revies the informations about genes involved in symbiotic nitrogen fixation, developmental processes in which host plant interact with microbe during nodule formation were introduced first. The structure, function and regulation of the genes discussed were mainly about microbial genes; those involved in the process of nodule formation (nod-genes) and of nitrogen fixation (nif-genes). Informations about the host genes involved in the symbiosis were discussed briefly.

• KSBB Journal
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• v.20 no.6
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• pp.418-424
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• 2005

Photoheterotrophic evolution of molecular hydrogen by Rhodobacter sphaeroides is mediated by nitrogenase that is regulated transcriptionally and post-translationally by ammonium ion. Two PII-like proteins, GlnB and GlnK, play key roles in mediating inhibition and repression of nitrogenase in the presence of ammonium ion. glnB and glnK of R. sphaeroides were interrupted to abolish the ammonium ion effect controlling nitrogenase. Ammonium ion effect was still observed in mutant having an interruption in either glnB or glnK. However, the nitrogenase activity of glnB-glnK double mutant is not affected by ammonium ion. $H_2$ evolution was improved by increasing gene dosages of nitrogenase-coding genes, nifHDK in trans in glnB-glnK double mutant.

• Journal of Microbiology and Biotechnology
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• v.20 no.5
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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.

• Nuclear Engineering and Technology
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• v.4 no.3
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• pp.203-213
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• 1972

The precipitation sequence of Inconel 718 alloy, aged at $760^{\circ}C$ for times up to 200 hr, has been studied by means of electron microscopy and X-ray diffraction methods. The dominant hardening phase was identified as the metastable, body-centered tetragonal $Ni_3Nb$ Phase in the morphology of platelets. The other phases identified in the aging sequence were (Nb, Ti)C and the stable acicular phase of orthorhombic $Ni_3Nb.$ The observations were made on the interaction of dislocations with the precipitates in the underaged condition. The shearing of the precipitates and the planar defects, e.g., stacking faults on i1101 planes of the intermetallic phase, were observed.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.88.2-88.2
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• 2010

2006년 2월 7일, Gemini North Observatory의 Near-Infrared Integral Field Spectrometer (NIFS)를 사용해 타이탄의 K-band 분광영상을 얻었다. NIFS의 파장분해능은 R~5,000이었고, 타이탄 disk의 적도부분은 약 16 pixel로 분해되었다. 2.0 - 2.1 micron 영역에서 미지의 분광선이 관측됐는데, 그 분광 구조는 전형적인 slightly asymmetric-top molecule의 rotational-vibrational 밴드 구조와 유사하게 나타났다. 또한 N2-N2 Collision-Induced Absorption (CIA)과 H2-N2 dimer에 의한 흡수와 메탄(CH4)가스 흡수를 포함한 분광모델을 만들어 비교한 결과 이 파장영역에는 이러한 흡수선들의 영향이 적은 것으로 확인됐다. 따라서 해당 영역의 저분산 (R~2,000 - 3,400) 스펙트럼을 토대로 액체 또는 고체 상태의 탄화수소가 타이탄에 존재한다고 보는 최근 발표된 주장들은 (e.g., Brown et al. 2008, Nature, v. 454, p. 607; Adamkovics et al. 2009, Planetary and Space Science, v. 57, p. 1586) 보다 신중히 고려돼야 한다.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.43.1-43.1
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• 2011

근적외영역의 타이탄 측광영상에서 나타나는 주연감광(Limb Darkening) 및 주연증광(Limb Brightening) 현상의 원인을 설명하기 위해 구면기하(spherical geometry)에 의한 효과 외에 헤이즈(haze) 자체의 성질 변화량을 추정해 본다. 근적외영역의 강한 메탄 흡수 밴드 부근에서 타이탄의 대기를 관측하면 파장에 따라 표면 부근에서 성층권 사이의 정보를 얻을 수 있으며, 이를 복사전달모델과 비교해 대기 중에 존재하는 연무 입자의 성질을 유추할 수 있다. 관측자료는 2006년 2월 Gemini/North Observatory의 Near-Infrared Integral Field Spectrometer(NIFS)를 이용해 얻은 측 분광 자료를 사용하였다. NIFS의 공간분해능은 화소당 0.05"로, 타이탄의 적도부분을 약 17화소로 분해할 수 있으므로, 각 지역별로 분광선 모델을 만들어 관측자료와 비교하는 데에 용이하였다.