• 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.

• 한국환경과학회지
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• 제21권9호
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• pp.1139-1147
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• 2012

To find out the growth conditions for the maximum activity of nitrogenase which catalyzes nitrogen fixation in Rhodobacter sphaeroides, the promoter activities of nifA and nifH were analyzed and the results indicated that expression of both nifA and nifH was increased in response to deprivation of both O2 concentration and nitrogen source. The nifA mutant was constructed by deleting the gene to investigate the effect of NifA, the transcriptional regulator, on the nifH and nifA expression in R. sphaeroides. Analysis of expression of nif genes using the nifA::lacZ and nifH::lacZ fusions in the nifA mutant revealed that NifA acts as a positive activator for nifH and an autoregulator in its own expression. The promoter activities of nifA and nifH in the prrA mutant grown under anaerobic and ${NH_4}^+$-free conditions were derepressed, comparing with those of the wild-type grown under the same conditions, indicating that the prrA product acts as a positive regulator in expression of nifA and nifH.

• 생명과학회지
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• 제22권8호
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• pp.1009-1017
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• 2012

Rodobacter sphaeroides에서 orf282 유전자는 cbb3 terminal oxidase를 암호화하는 ccoNOQP 오페론과 혐기적 활성자인 FnrL을 암호화하는 fnrL 유전자 사이에 있으며, 아직은 기능이 잘 알려지지 않았다. orf282 유전자의 기능을 알기 위해 우리는 orf282의 일부를 삭제함으로써 유전자를 붕괴시켜 orf282-minus mutant를 제조하였다. 두개의 FnrL 결합 부위가 orf282의 upstream에 존재한다는 것이 밝혀져 있으며, orf282 유전자가 FnrL에 의해 양성적으로 조절된다는 것이 증명되었다. orf282 유전자는 B875와 B800-850 spectral complexes의 형성과 관련이 없다. orf282 mutant에서의 cbb3 oxidase 활성을 wild type와 비교해보면 orf282 유전자가 ccoNOQP 오페론의 조절과 cbb3 cytochrome c oxidase의 생합성과 무관하다는 것을 알 수 있다. orf282 mutant의 구조 유전자인 nifH와 조절유전자인 nifA의 프로모터 활성이 증가한 것은 orf282 유전자 산물이 nifH와 nifA의 발현에서 음성적 effector로 작용한다는 것을 시사한다.

• 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.

• 한국미생물·생명공학회지
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• 제31권1호
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• pp.18-24
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• 2003

벼과식물과 관련된 질소고정균을 분리하기 위하여 한반도 남부지방의 19지역에서 쌀, 밀, 귀리, 보리, 호밀, 옥수수 등을 채집하여 이들의 뿌리로부터 free living bacteria와 endophyte를 분류하였다. Colony의 형태, 크기, 색깔 등과 16S rDNA 염기서열을 근거로 63종으로 분류하였다. nifH 유전자 염기서열 결정과 nitrogenase 활성 측정을 통하여 분리균주 모두 질소고정 능력이 있음을 확인하였다. 그리고 식물에서 분리한 내생균의 특징 중 하나인 cellulase활성이 대부분의 분리 균주에서 확인되었다.

• 한국미생물·생명공학회지
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• 제34권1호
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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.

• KSBB Journal
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• 제20권6호
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• pp.418-424
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• 2005

Rhodobacter sphaeroides는 photoheterotrophic 조건에서 성장을 하면서 질소고정효소인 nitrogenase에 의해 수소를 발생시킨다. 이 nitrogenase는 ammonium ion이 존재할 때, PII 계열 단백질인 GlnB와 GlnK에 의해 negative regulation을 받게 된다. 본 연구에서는 glnB와 glnK 유전자를 interruption하여 수소생성의 증진을 꾀하였다. 그 결과, parental strain이나 glnB 혹은 glnK 유전자 하나만을 interruption 시켰을 경우, 암모니움 이온에 의해 nitrogenase 활성이 저해를 받고 있었으나, glnB, glnK 모두를 interruption 시켰을 때, 암모니움 이온에 의한 저해 효과가 줄어드는 것을 볼 수 있었다. 또한 이러한 glnB-glnK double mutant에 nifDK gene을 in trans로 넣어 nitrogenase의 dosage를 높였을 경우, 수소 생성이 약 30% 가량 증진되었다는 것을 볼 수 있었다.

• 생명과학회지
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• 제17권5호
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• pp.723-727
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• 2007

본 연구는 H. pylori에서 metronidazole내성에 관여하는 유전자를 발견하고 이들 유전자들의 상호 조절 기전을 밝힘으로서 위장질환의 원인균인 H. pylori를 퇴치하기 위한 기본바탕을 마련하고자 수행되었다. 우선적으로 metronidazole 내성을 조절하는 유전자인 fdxA(ferredoxin)에 의한 metronidazole 내성 조절 기전을 밝히기 위하여 다음의 연구를 수행하였다. Type I 균주인 26695균주의 fdxA 유전자에 chloramphenicol 내성 유전자를 삽입하여 결손돌연변이주를 구축하였다. fdxA의 비활성화에 의한 rdxA 및 frxA 유전자의 발현을 알아보기 위하여 2-D electrophoresis와 MALDI-TOP-MS을 이용하여 fdxA 유전자의 비활성화에 의해 over-expressed protein과 under-expressed protein을 검색하였다. 본 실험의 결과로 type I 균주인 26695에서 fdxA 유전자를 비활성화시킨 결과 frxA 유전자의 발현양이 증가함을 northern으로 확인하였으며, 또한 fdxA유전자의 downstream에 위치한 유전자들이 H. pylori의 생존에 중요한 역할은 한다는 것을 알 수 있었다. 또한 2-D electrophoresis와 MALDI-TOP-MS을 이용하여 fdxA 유전자의 inactivation에 의해 over-expressed protein으로 nifU-like protein(HP0221), frxA(HP0642), nonheme ferritin(HP0653)와 아직 기능이 밝혀지지 않은 hypothetical protein(HP0902) 등이 발견되었다. 그리고 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase(HP0089), (3R)-hydroxymyristoyl ACP dehydratase(HP1376)과 thioredoxin(HP1458)등이 under-expressed protein으로 발견되었다.

• Journal of Species Research
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• 제9권3호
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• pp.210-217
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• 2020

Microseira wollei (Farlow ex Gomont) G.B.McGregor and Sendall ex Kennis, a mat-forming filamentous harmful cyanobacterium, has historically been found in the United States. Microseira wollei produces neurotoxins and hepatotoxins which affect declining water quality. In the present research, we report of unrecorded M. wollei with morphology, TEM anatomy, molecular phylogeny on the Korean population. Based on 16S rRNA gene sequences, Korean population were different by 0.02% (2 bp) to the Japanese population, 1.2-1.3% to the Australian population, and 2.5-3.7% to the United States populations. nifH gene sequences were 8.4-8.7% different to Australian ones and 3.5-3.8% to other population, however molecular phylogenetic analysis of M. wollei living in Korea revealed monophyly with the geographical populations of U.S.A., Australia, and other geographical populations. Since the mat of M. wollei has been reported to be maintained for several years in other countries, it is necessary further investigate the seasonal and regional distribution of this species in Korea.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1286-1298
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• 2005

The genus Paenibacillus is a new group of bacilli separated from the genus Bacillus, and most of species have been isolated from soil. In the present study, we collected 450 spore-forming bacilli from the roots of winter crops, such as barley, wheat, onion, green onion, and Chinese cabbage, which were cultivated in the southern part of Korea. Among these 450 isolates, 104 Paenibacillus-like isolates were selected, based on their colony shape, odor, color, and endospore morphology, and 41 isolates were then finally identified as Paenibacillus spp. by 16S rDNA sequencing. Among the 41 Paenibacillus isolates, 23 were classified as P. polymyxa, a type species of the genus Paenibacillus, based on comparison of the 16S rDNA sequences with those of 32 type strains of the genus Paenibacillus from the GenBank database. Thirty-five isolates among the 41 Paenibacillus isolates exhibited antagonistic activity towards plant fungal and bacterial pathogens, whereas 24 isolates had a significant growth-enhancing effect on cucumber seedlings, when applied to the seeds. An assessment of the root-colonization capacity under gnotobiotic conditions revealed that all 41 isolates were able to colonize cucumber roots without any significant difference. Twenty-one of the Paenibacillus isolates were shown to contain the nifH gene, which is an indicator of $N_{2}$ fixation. However, the other 20 isolates, including the reference strain E681, did not incorporate the nifH gene. To investigate the diversity of the isolates, a BOX-PCR was performed, and the resulting electrophoresis patterns allowed the 41 Paenibacillus isolates to be divided into three groups (Groups A, B, and C). One group included Paenibacillus strains isolated mainly from barley or wheat, whereas the other two groups contained strains isolated from diverse plant samples. Accordingly, the present results showed that the Paenibacillus isolates collected from the rhizosphere of winter crops were diverse in their biological and genetic characteristics, and they are good candidates for further application studies.