• Applied Biological Chemistry
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• v.48 no.3
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• pp.189-200
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• 2005

Biological nitrogen fixation is an important process for academic and industrial aspects. This review will briefly compare industrial and biological nitrogen fixation and cover the characteristics of biological nitrogen fixation studied in Azotobacter vinelandii. Various organisms can carry out biological nitrogen fixation and recently the researches on the reaction mechanism were concentrated on the free-living microorganism, A. vinelandii. Nitrogen fixation, which transforms atmospheric $N_2$ into ammonia, is chemically a reduction reaction requiring electron donation. Nitrogenase, the biological nitrgen fixer, accepts electrons from biological electron donors, and transfers them to the active site, FeMo-cofactor, through $Fe_4S_4$ cluster in Fe protein and P-cluster in MoFe protein. The electron transport and the proton transport are very important processes in the nitrogenase catalysis to understand its reaction mechanism, and the interactions between FeMo-cofactor and nitrogen molecule are at the center of biological nitrogen fixation mechanism. Spectroscopic studies including protein X-ray crystallography, EPR and $M{\ddot{o}}ssbauer$, biochemical approaches including substrate and inhibitor interactions as well as site-directed mutation study, and chemical approach to synthesize the FeMo-cofactor model compounds were used for biological nitrogen fixation study. Recent research results from these area were presented, and finally, a new nitrogenase reaction mechanism will be proposed based on the various research results.

• Microbiology and Biotechnology Letters
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• v.13 no.3
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• pp.251-255
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• 1985

Nitrogen-fixing bacteria were isolated from the rice rhizosphere of various paddy fields in our country. The screening of 235 isolates for nitrogen-fixing ability resulted in the isolation of Enterobacter agglomerans NFB264 and three Klebsiella pneumoniae NFB 3, NFB 320. Plasmids of various molecular weight from 1.7 to more than 84 Mal. were detected by agarose gel electrophoresis in three out of four isolates. But, these plasmids had not any nitrogen-fixing genes. Hybridization experiments using Klebsiella pneumoniae M5al nitrogen-fixing genes, nif Q-K and nif DH, as probes revealed the presence of homologous sequences in the chromosomal DNA of all isolates. However the restriction patterns of nif genes of the isolates by various restriction endonucleases were different to those of Klebsiella pneumoniae M5al.

• Journal of Aquaculture
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• v.10 no.1
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• pp.69-76
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• 1997

Chromatium sp., densely populated on the bacterial plate of Lake Kaiike throughout the seasons, possibly fix N2 and concurrently produce H2 N2 Fixation and H2 production by Chromatium sp. were performed under photoautotrophic growth condition, and of which rates were much higher and showed expontial growth phase. Bacterial plater samples from Lake Kaiike collected on July 27, 1994 were used to know the effect of the light or H2S on N2 fixation and H2 productin by the bacteria. At low light intensity (250 lux), low rates of N2 fixation and H2 production were detected after 18 hours. However, high rates of the production were observed under the condition of high light intensity (1000 lux). On the other hand, a very low rate of N2 fixation was observed without an addition of H2S, while the bacterial rapilly increased N2 fixation and H2 production after adding H2S and the highest rate was observed in case of adding 20mg H2S-S/$m\ell$ to the bacterial plates.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.1
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• pp.47-48
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• 1979

To study on the state of nitrogen fixation of Lemma associated with blue green algae this experiment was carried out. The results were as follows: 1) The blue green algaes associated with Lemnaceae were mainly Calthrix sp. and Microcrate sp., but Anabaena sp. was found only in L. gibba. 2) It was believed that Lemnaceae associated with blue green algae have semi-symbiotic nitrogen fixation ability, especially clear in L. oligorhiza.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.3
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• pp.286-293
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• 1983

The glucose application remarkably increased the heterotrophic acetylene reducing activities during one month incubation. The amount of the increases varied between the soils. Application of rice straw brought about the significant increases during incubation time. Compost contained the largest amount of available-N among the C-sources, and thereby brought the smallest increase in all soils. The cumulative fixed nitrogen with application of rice straw at 30 days incubation in the three experimented soils were highest in Hwadong clay soil, i.e, $2.2mg^N/100g$, intermediate in Ratchaburi soil $0.85mg^N$, and least in Konosu soil $0.80mg^N/100g$. On the other hand, nitrogen fixing heterotrophic, bacteria, such as Clostridia, aerobes and anaerobes, were remarkably increased by application of rice straw while Azotobacter and Beijerinkia were not. The cumulative fixed nitrogen was more pronounced in the clay soil than in the coarse loamy soil. More pronounced nitrogen fixing activities in light condition(heterotrophic + photosynthetic) than that in dark(heterotrophic) condition have been observed both in the coarse loamy and clay soils. The nitrogen fixing ability of photosynthetic microbes in paddy soil is probably higher in coarse loamy soil than in clay soil.

• Journal of Life Science
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• v.12 no.5
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• pp.544-548
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• 2002

The object of this study was to investigate nitrogen fixation activity of rhizobium inoculated at seed coat when drought condition was applied in flowering period of soybean c.v. Samnamkong. The rhizobia used in this experiment were indigenous rhizobium, R2l4, RJl-29, USDA110 and USDA122. The experiment was done with 1/2000 Wagner pots in laboratory and greenhouse and was tested in completely randomized design with four replications. Nitrogen fixation activity in coventional culture was the highest in R2l4 and indigenous rhizobium among the five rhizobia strains. As given drought condition from flowering to maturity, nitrogen fixation activity was higher in R2l4 and RJl-29 than indigenous rhizobium. Leaf area and relative index (drought/convention) of pod weight were higher in USDA122, RJl-29 and R2l4 than indigenous rhizobium as given drought condition from flowering to maturity. High positive correlation was observed between nitrogen fixation activity of rhizobium and relative index(drought/convention) of pod weight. High negative correlation was observed between respiration of plant and relative index (drought/convention) of leaf area.

• The Microorganisms and Industry
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• v.14 no.3
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• pp.23-26
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• 1988

자연계에 있어서 질소는 대기중의 분자상질소를 비롯하여 초산, 암모니아와 같은 무기태질소, 단백질, 핵산 등의 유기태질소 등 다양한 형태로 존재하며 생물권내에서 흡수, 고정, 대사, 분해되는 등 다양한 순환을 거듭하고 있다. 대기중의 분자상질소는 Rhizobium, Azotobacter, Klebsielle, Clostridium, Blue-green algae 및 광합성세균 등에 의해 고장되어 암모니아의 형태로 환원된다. 한편 대부분의 식물들은 초산이나 암모니아 형태의 질소를 흡수 동화하여 핵산, 단백질을 만들고 이들 구성물은 사후 암모니아로 재분해 된다. 또한 동식물의 유체내지는 배설물들도 각기 분해되어 암모니아의 형태로 변화되는데 이와같은 일련의 질소순환(nitrogen cycle)은 초화세균, 탈질세균 내지는 질소고정균등 대부분의 미생물에 의해 크게 지배를 받고 있다.

• Korean Journal of Soil Science and Fertilizer
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• v.14 no.1
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• pp.44-50
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• 1981

A pot experiment was conducted to find the nitrogen fixing activities associated with ice rhizoplane in nine varieties at various growth stage by acetylene reduction technique. Results obtained ware Summarized as follows. 1. Nitrog en fixing activites associated with rice rhizoplane differ by the rice variety and the growth stage. The activities increased with progressing of growing time, and maximum activities were obtained from the ear forming stage to the heading stage. 2. The application of rice straw did not greatly enhanced the nitrogen fixing activities associated with rice rhizoplane. However, somewhat increasing tendency was obtained in the Kataktara, TKM-6, Centrypartna. Daegujo, and Jodongji varieties. 3. The nitrogen fixed during the one rice cropping period was estimated as 0.55kg of N per 10a by Milyang-23 variety to 2.6kg of N per 10a by Jodongji variety. 4. The amount of rice root showed no significant relationship with the amount of nitrogen fixed during the growing period of rice plant.

• Microbiology and Biotechnology Letters
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• v.46 no.2
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• pp.154-161
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• 2018

Currently, urban greening projects and research are attracting attention as a way to mitigate urban heat island phenomenon. In this study, nitrogen fixative bacteria were isolated and their effects on plant growth were confirmed. First, enrichment was performed in a nitrogen-free medium to isolate the nitrogen-fixing bacteria, and the colony showing high growth in a medium with limited nitrogen source was isolated and purified. Separated bacterial isolates were reduced by more than 90% acetylene by ARA and indirectly confirmed the activity of nitrogenase by ethylene production. Cedecea sp. MK7 and Enterobacter sp. Y8 with confirmed reproducibility were selected as nitrogen fixative bacteria. Nitrogen fixing bacteria were applied to the growth of perennial rye grass, and it was found that the dry weight increased to 34.80 mg (186.60%) compared with the control with 18.65 mg dry weight. After plant growth, microbial community analysis of soil applied by bacteria showed similarity to the control group. Therefore, in this study, it is expected that the efficiency will be increased if plant growth is promoted by using nitrogen fixing bacteria in urban greenery system.

• Microbiology and Biotechnology Letters
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• v.13 no.1
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• pp.79-85
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• 1985

Rhizobium japonicum wild type strains isolated from local soybean variety Jangback root nodules with higher nitrogenase activity than R. japonicum 3I1110 or 61A76 was mutangenized by N-methyl-N'-nitro-N-nitrosoguanidine and UV-irradiation, and screened by effectiveness assay with soybean. One mutant strain JB65 nodulated the roots earlier than the wild type and also expressed higher acetylene-reducing activity in the presence and absence of fixed nitrogen. The selected mutant was compared with SM35 strain and showed greater nodulation and symbiotic nitrogen fixing activity with local soybean variety Jangback than SM35 strain.