• Korean Journal of Soil Science and Fertilizer
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• v.23 no.3
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• pp.220-226
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• 1990

This experiment was carried out to study the effects of Bradyrhizobium moculation and fertilizer N application on symbiotc $N_2$ fixation of peanut (Arachis hypogaea L. cv. Younghotangkong) at newly reclaimed soil. Treatments consisting of B. sp. (Vigna) HCR-3 and HCR-46 with control and five levels of nitrogen (0, 4, 8, 16, 32kg/10a) were arranged with split design of four repetitions. The results obtained were as follows. The number of viable Bradyrhizobium in rhizosphere was decreased to 20 days after sowing and thereafter it was remarkably increased, until full ripe stage of pods, decreased as fertilizern rates increased. Nodulation and nitrogenase activity were reduced with increasing levels of fertilizer, whereas top dry matter and nitrogen accumulation where increased. Seed yield of Bradyhizobium inoculation under the fertilizer N zero level was similar to that N : 8kg/10a under uninoculation. It suggested that Bradyrhizobium inoculation could replace the effect of nitrogen application.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.387-393
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• 1992

The fate of inoculum strain of Bradyrhizobium japonicum was studied by using genetically marked strain. RJB6 $str^rnal^rneo^r$. A spontaneous mutant of B. japonicum isolated from nodules was made to have antibiotic resistance against streptomycin and nalidixic acid. In order to make genetically marked strain, neomycine resistant gene(Tn5) was introduced into this spontaneous mutant by conjugation with E. coli containing pSUP2021. The southern hybridization was carried out to confirm the plasmid insertion. Hybridization of chromosome DNA using pSUP2021(Tn5) as a probe showed that Tn5 was located on the 4.9kb fragment of chromosome. Soybean seeds were planted into a soil previously cultivated with soybean and inoculated with different cell densities of marked strain. Fourty days after planting, the inoculation effects on nodule number, nodule fresh weight, plant height and nitrogen content in the plot inoculated with heavy cell suspension was a little better than those in the plot with low inoculation. The recovery percentage of the marked strains was about 12% in the plot inoculated with heavy density cell suspension, while 5% in the plot inoculated with low cell suspension.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.378-386
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• 1992

This experiment was conducted to investigate the effects of inoculation of the Bradyrhizobium sp.(Arachis) HCR-46 and fertilizer nitrogen application on nodulation, $N_2$-fixation of cowpea group legume(Seowon dongbu, Seonwha nogdu, Chungju pat, Youngho tangkong). Treatments consisted of five uninoc.+N : O, uninoc.+N : 6kg/10a. inoc.+N : O, inoc.+ N : 6kg/10a, inoc.+N : 12kg/10a. 1. Initial nodulation time of cowpea group legume by inoculation of Bradyrhizobium sp. HCR-46 was 12~21 days, and it was delayed as more fertilizer nitrogen was added. 2. The number and dry weight of nodule were increased as growth period elapsed, but decreased as fertilizer nitrogen was added. 3. Dry matter production and amount of nitrogen uptake were increased by inoculation and the effects of inoculation were increased when fertilizer nitrogen of 6kg/10a was applied. 4. Amount of fixed nitrogen by inoculation of fertilizer nitrogen not applied was higher than the case of 6kg/10a applied and that of peanut was higher than the other legumes(cowpea, mung bean and adzuki).

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.1
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• pp.60-66
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• 1996

Bradyrhizobium japonicum with different colony morphology populated in five Yeongnam soils of Korea was examined for intrinsic antibiotic resistance to eight antibiotics, serological property by immunoblot and immunodiffusion, and protein profile differentiation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Colony morphological distribution of one hundred and twenty B. japonicum isolates was 47% for "dry". 41% for "wet", and 12% for "dry/wet" type. The total isolates showed such a strong correlation between the morphology and antibiotic resistance. Colony morphology, which though was dominantly consisted of the same type within a serogroup, wasn't absolutely linked to serological property of B. japonicum. Based on these data, colony morphology was too simple to identify variations with B. japonicum isolates : antibiotic resistance such complicated compared with serological analyses.

• Journal of Environmental Health Sciences
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• v.42 no.4
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• pp.274-279
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• 2016

Objectives: We investigated bacterial diversity in the Han River water resource protection area in order to provide basic microbiological information on the drinking water safety of the Seoul metropolitan region. Methods: Samples were collected in the spring and winter, but not during the rainy season. Pyrosequencing, gene amplification, and extraction of nucleic acids were employed in this study. Results: In total, 57 and 48 operational taxonomic units were respectively analyzed in samples collected during spring and winter. Proteobacteria were predominant in all samples. The samples contained phylogenetically diverse bacterial communities, with eleven major phyla and 36 genera. Cyanobacteria were predominant in the spring samples, but not in the winter samples. The predominant species in the samples collected during both seasons belonged to the genus Aquamicrobium and Bradyrhizobium. Moreover, no pathogenic bacteria were detected in the samples. Conclusion: Proteobacteria were predominant in the samples from the Han River water source protection area. Cyanobacteria were more predominant in the spring samples than in the winter samples, but Aquamicrobium and Bradyrhizobium were predominant in both sampling seasons.

• Korean Journal of Microbiology
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• v.32 no.1
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• pp.1-6
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• 1994

DNA-DNA hybridization by kinetic method was carried out between species of purple nonsulfur photosynthetic bacteria and nonphotosynthetic bacteria. The degrees of homology percent were shown to be low (2-35 D%) with the exception of high homology % (72-88 D%) for strains within a species and between Rhodobacter capsulatus and Rhodopseudomonas blastica. The D% between the purple nonsulfur photosynthetic bacteria, Rhodopseudomonas palustris, and nonphotosynthetic bacteria, Pseudomonas aeruginosa ATCC 27853 or Bradyrhizobium japonicum were a little higher (26-33 D%) than the D% between any other photosynthetic bacteria. The homology % between Rhodopseudomonas blastica and Rhodobacter capsulatus was 72 D%, which showed genetic relationship.

• Korean Journal of Organic Agriculture
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• v.14 no.4
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• pp.411-420
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• 2006

Indole-3-acetic acid (IAA) biosynthesis by bacteria occurs widely in rhizospheres. Bacterial species able to synthesize IAAmay be exploited for beneficial interactions in crop management systems. The objective of this study was to determine the response of ivyleaf morningglory (Ipomoea hederacea) seedlings to IAA and to an IAA-producing rhizobacterum, Bradyrhizobium japonicum isolate GD3. IAA solution and isolate GD3 suppression of seedling growth measured as radicle length and biomass depended on IAA concentration. Seedling radicle length was significantly reduced by ca. 29% with more than $1.0{\mu}M$ of IAA solution, compared to the control, 48 h after application. The cell concentration at 50% growth reduction ($GR_{50}$) of the seedling radicle was IAA production by isolate GD3 at $10^{4.82}\;cfu$, the cell concentration for 50% growth reduction ($GR_{50}$) of seedling radicle was 0.24 iM, which was much lower than the IAA solution concentration ($117.48{\mu}M$) required for $GR_{50}$. Therefore, excess IAA production by isolate GD3 may be more detrimental to morningglory radicle growth than standard IAA solution. Results confirmed involvement of IAA in suppressive effects of isolate GD3 on morning-glory seedlings grown in a hydroponic system.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.1
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• pp.62-67
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• 1999

As a basic experiment to enhance the symbiotic utility of atmospheric nitrogen on soybean, host affinities and serological distribution of Bradyrhizobium japonicum indigenous to five Korean upland soils were measured. Based on nodulation, the symbiotic affinities between indigenous B, japonicum and eight soybean cultivars were remarkably different among soil inocula. On the whole, the averaged affinities of B. japonicum populations to soybeans were favorable in order of Goseong > Milyang > Suweon soils, but those in Iksan and Namjeju soils were not, especially for Danweonkong, Jangkyeongkong, and Eunhakong soybean cultivars. Regression analyses between nodules mass and shoot dry weight of soybean yielded model with $R^2=0.51$ for Goseong, $R^2=0.45$ for Milyang, $R^2=0.38$ for Iksan, $R^2=0.28$ for Namjeju, and $R^2=0.24$ for Suweon soils. B. japonicum from sampled soils were serologically fell into more than seven serogroups such as YCK 117(34.1%), YCK 141(6.5%), YCK 321(6.5%), YCK 445(4.7%), YCK 338(2.9%), YCK 150(1.2%), YCK 258(0.6%). The dominant serogroup YCK 117 was distributed 51.9 for Namjeju, 45.8 for Goseong, 41.7 for Iksan. 34.2 for Sueveon, and 11.1% for Milyang soils.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.3
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• pp.275-283
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• 1987

In order to find out the effectiveness of nitrogen fixation in rhizobia-legume symbiotic relationship, ecological and physiological characteristics of indigenous rhizobia distributed in Korean soils, that is, dissimilatory nitrate reduction patterns of indigenous soybean rhizobia isolated from four different soils, and differences in one-and two-dimensional polyacrylamide gel electrophoretic pattern of proteins among the each subgroups of Bradyrhizobium japonicum and Rhizobium fredii, were investigated. The results were summarized as follows: 1. The indigenous soybean rhizobia isolated from four different soils could be classified into 4 groups depending on growth rate and dissimilatory nitrate reduction pattern, that is, $S_1$ (slow-grower; Bradyrhizobium japonicum and nitrate denitrifier), $S_2$ (slow-grower; Bradyrhizobium japonicum and nitrate respirer), $F_1$ (fast-grower; Rhizobium fredii and denitrifier), and $F_2$ (fast-grower; Rhizobium fredii and nitrate respirer). 2. The population ratio of fast- to slow-growing R. japonicum was 39% to 61%, and the ratio of denitrifier to nitrate respirer was 31% to 69% and 89% to 11% in fast and slow-grower, respectively. Some differences were observed between fast- and slow-growing R. japonicum but no significant difference was observed between denitrifier and nitrate respirer within same growth type by one and two dimensional SDS-polyacrylamide gel electrophoretic patterns.

• Bulletin of the Korean Chemical Society
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• v.28 no.2
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• pp.347-350
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• 2007