• 한국토양비료학회지
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• 제45권4호
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• pp.593-601
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• 2012

Heavy metals and metalloids removal can be considered as one of the most important world challenges because of their toxicity and direct impact on human health. Many processes have been introduced but biological processes of remediation seem to offer the most suitable solution in terms of efficiency and low cost. Actinobacteria constitute one of the major microbial populations in soil, and this can be attributed to their adaptive morphological structure as well as their exceptional metabolic power. Among microbes, actinobacteria are morphologic intermediate between fungi and bacteria. Studies on microbial diversities in metal contaminated lands have shown that actinobacteria may constitute a dominantly active microbiota in addition to ${\alpha}$ Proteobacteria. Furthermore, isolation studies have shown metal removal mechanisms which are reminiscent of notable multiresistant strains, such as Cupriavidus metallidurans. Apart from members of genus Streptomyces, which produce more than 90% of commercialized antibiotics, and the nitrogen fixing Frankia, little attention has been given to other members of this phylum. This is because of difficult culture condition requirements and maintenance. In this review, we focused on specific isolation of actinobacteria and their potential applications in metal bioremediation and plant growth promotion.

• Journal of Microbiology and Biotechnology
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• 제10권2호
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• pp.119-136
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• 2000

Being autotrophic, algae occupy a trategic place in the biosphere. They produce oxygen both directly and indirectly through the chloroplasts of all green plants. The chloroplasts are believed to have originated from archaic prokaryotic algae through endosymbiosis with primitive eukaryotic cells. Phytoplankton and other algae regulate the global environment not only by releasing oxygen but also by fixing carbon dioxide. They affect water quality, help in the treatment of sewage, and produce biomass. They can be used to produce hydrogen which is a clean fuel, and biodiesel, and fix $N_2$ for use as a biofertilizer. Some other services of algae to the environment include restoration of metal damaged ecosystems, reducing the atmospheric $CO_2$ load and citigating global warming, reclamation of saline-alkaline unfertile lands, and production of dimethyl sulphide (DMS) and oxides of nitrogen (NOx) involved in the regulation of UV radiation. ozone concentration, and global warming. Algae can be valuable in understanding and resolving certain environmental issues.

• 미생물학회지
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• 제32권1호
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• pp.7-11
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• 1994

미산소성 세균으로 알려진 질소고정균 Arcobacter nitrofigilis는 brucella 액체배지에서 호기적 생장의 특성을 나타내었다. 일반대기의 산소조건(21% $O_2$)하에서 최대생장의 특성을 보여주었다. 2% 이하의 산소조건하에서 산소 이외의 다른 최종산소수용체를 첨가하지 않은 액체배지에서 이 세균은 적은 정도의 생장을 나타내었다. 이 세균은 전자전달계 구성성분인 세포막에 함유되어 있는 cytochrome b 및 c, 그리고 용해성 cytochrome c를 가지고 있었다. 일반대기의 산소조건에서의 최대생장, 낮은 산소 농도하에서의 적은 정도의 생장 및 cytochrome c의 존재로 볼 때 이 세균은 미산소성 세균이나 통성혐기성 세균이 아니고, 호기성 세균임을 나타내주며, 또한 이 세균은 산소를 이용한 호픕에 의해 에너지를 얻음을 나타내준다.

• Journal of Ecology and Environment
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• 제29권2호
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• pp.151-155
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• 2006

Root nodule biomass, and seedling biomass and growth were examined for 2-year-old Robinia pseudoacacia and Amorpha fruticosa seedlings following fertilization treatments. Organic fertilizer, solid combination fertilizer, and organic fertilizer plus solid combination fertilizer were used for the study. Root nodule biomass (g/plant) ranged from 3.00 to 7.06 for R. pseudoacacia and varied from 1.52 to 2.32 for A. fruticosa, respectively. In all treatments, root nodule biomass of R. pseudoacacia was significantly higher than those of A. fruticosa. Fertilization significantly increased root nodule biomass for only R. pseudoacacia, however, there were no significant differences in root nodule biomass among fertilization treatments. Root nodule biomass was not influenced by soil nitrogen (N) and phosphorous (P) concentrations following fertilization treatments. Seedling biomass (components and total) and growth (diameter at root collar and height) were strongly correlated with root nodule biomass for the two N fixing tree species.

• Journal of Plant Biotechnology
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• 제1권1호
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• pp.31-38
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• 1999

An artificial symbiosis was established between diazotropic Azomonas insignis and strawberry (Fragaria x ananassa). The partnership was created by in vitro techniques through callus induction and organogenesis. The basis of this partnerships is the bacterial dependence on the plants metabolic activity, using maltose in the medium as a carbon and energy source which can be utilized by the plant cells only. The presence of bacteria in the intercellular spaces of the callus tissues and regenerated plants was proven by microscopic techniques. Nitrogenase activity could also be detected in the plant tissues. For successful and high frequency introduction of bacteria to the plant tissues, biolistic gun method was used. On the basis of the DNA transfer method, Azotobacter vinelandii bacteria were delivered directly into strawberry tissues by the particle bombardment. This was the first use of living bacteria as microprojectils for bombardment of plant tissues. The treatment was successful, the presence of bacteria in the developing callus tissue and regenerated plants were detected by light and electron microscopy.

• 한국작물학회지
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• 제49권4호
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• pp.316-324
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• 2004

Sinorhizobium sp. strain MUS10 forms nitrogen-fixing stem nodules on Sesbania rostrata, a tropical green manure crop. In this study, the ultrastructural events associated with the formation of stem nodules were investigated. Sinorhizobium sp. strain MUS10 entered the host tissue through cracks created by the emerging adventitious root primordia and multiplied within the intercellular spaces. During early phases of infection, host cells adjacent to invading bacteria revealed cellular damage that is typical of hypersensitive reactions, while the cells at the inner cortex exhibited meristematic activity. Infection threads were numerous in S-day-old nodules and often were associated with the host cell wall. In several cases, more than one infection thread was found in individual cells. The junction at which the host cell walls converged was often enlarged due to fusion of intracellular branches of infection threads resulting in large infection pockets. The infection threads were made up of a homogeneous, amorphous matrix that enclosed the bacteria. Several finger-like projections were seen radiating from these enlarged infection threads and were delineated from the host cytoplasm by the plasma membrane. As in Azorhizobium caulinodans induced root nodules, the release of Sinorhizobia from the infection threads into the plant cells appears to be mediated by 'infection droplets'. A 15-day­old Sesbania stem nodule revealed typical ultrastructure features of a determinate nodule, containing several bacterioids within symbiosomes.

• 한국작물학회지
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• 제46권5호
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• pp.416-419
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• 2001

Hypernodulation soybean mutant, SS2-2, is characterized with greater nodulation and nitrogen fixing ability in the root nodule than its wild type, Shinpaldalkong 2. The present study was performed to identify a genetic locus conferring hypernodulation in soybean mutant SS2-2 and to determine whether the gene controlling the hypernodulation of SS2-2 is allelic to that controlling the supernodulation of nts382 mutant. Hybridization studies between SS2-2 and Taekwangkong revealed that the recessive gene was responsible for the hypernodulation character in soybean mutant SS2-2. Allelism was also tested by crossing supernodulating mutant nts382 and hypernodulating mutant SS2-2 that both hypernodulation and supernodulation genes were likely controlled by an identical locus. Molecular marker mapping of hypernodulation gene in SS2-2 using SSR markers confirmed that the gene conferring hypernodulation was located at the same loci with the gene conferring supernodulation. It is interesting to note that the same gene controlled the super- and hyper-nodulation characters, although SS2-2 and nts 382 exhibited differences in the amount of nodulation in the root system. Further genetic studies should be needed to clarify the genetic regulation of super- and hyper-nodulation in soybean.

• 한국동물학회:학술대회논문집
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• 한국동물학회 1995년도 한국생물과학협회 학술발표대회
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• pp.120-120
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• 1995

The total size of the pF AR1, a genomic clone of Frankia FaCI, was estimated to be about 44Kb by summation of the individual fragment length generated by single or double restriction enzymes. Southern hybridization analyses with Azotobacter vinelandii nif-genes as probes and partial sequencing analyses of the subclones revealed that organization of the nif-gene in the FaCI strain was nifV, H, D, K, E, N, X, W, B. The organization of the structural genes for nitrogenase is the same in this Frankia strain as it is in most other nitrogen-fixing prokaryotes but the positioning of the nifV-like gene relative to the nifHDK cluster differs. A consensus nif-promoter-like sequence, found at 5' of nifH, was not detected upstream of the niJV-like gene. nifV-like gene contained a ORF of 1206 NT encoding 401 amino acids. The nucleotide sequence and deduced amino acid sequence of the gene exhibit homology value of 65% and 41% with that from A vinelandii, respectively. The putative Shine-Dargamo sequences were present preceding nitK, nifH, D, K, and nifE, and in nitK gene putative start codon GTG was detected instead of A TG. The nucleotide and amino acid sequence of niIK of FaCI showed 82% and 76% homolgy with those of Frankia HFPCc 13, respectively. Amino acid sequence of niIK showed 69% and 61% homology with those of A vinelandii, Klebsiella pnewnoniae, respectively, while that of nifE 73% and 71%, respecti vely.i vely.

• 미생물학회지
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• 제27권1호
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• pp.21-26
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• 1989

한국산 Klebsiella pnelµnoniae KNFl의 chromosomal DNA를 Hind III로 부분소화하고 pBR 322도 같은 효소로 완전소화했다. 소화된 pBR 322 의 5'- 말단연산기를 제거하여 두 DNA 표품을 ligation 한 후 E. coli K060 으로 transformation 하 였다. 이러한 transformants중 N-free 한천배지에서 자라는 단일 colony을을 얻었으며, 이들은 모두 ampicillin에 대해 저 항성을 가지고 있었고 tetracycline에 대해 저항성이 없었으며 cunng 되였을 때는 질소고정능을 잃었다. 이런 사실로부터 이 transformants가 K. pneumoniae의 질소고정능 유전자을 포함하는 recombinant plasmid를 가지고 있음을 확인할 수 있었다. 이들 transformants의 nitrogenase 역가는 K. pneumoniae KNF 1보다 더 높았다.

• The Korean Journal of Ecology
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• 제19권3호
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• pp.209-216
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• 1996

In order to identify the habitat characteristics of water shield (Brasenia schreberi), water quality and sediment characters were investigated. Water shield had peculial habitats such as old reservoir, developed basin-like reservior, a water depth within 1.5 m, constant water level, and thick sediment layer at the bottom. The species had very dense populations under the favorable growing conditions and occasionally grew together with Utricularia japonica. When water shield decreased, Nelumbo nucifera, Nuphar japonicum and Zizania latifolia increased. Natural populations of water shield need protection because it is endangered by the human activities and their harvest. The optimal conditions for the growth of water shield was near neutral pH. low conductivity and low turbidity. Therefore the input of pollutants should be controlled for its growth. The inorganic ion contents such as K, Mg, and Na were higher in the water shield growing area. Especially iron content of the sediments in the reservoirs with water shield was nearly five times as high as that in the reservoirs without water shield. thus iron might be one of the major limiting factors for the growth. It was considered that molybdenum can be another major factor because water shield is a nitrogen fixing plant.