• KSBB Journal
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• 제19권4호
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• pp.331-334
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• 2004

재조합 E. coli를 이용한 MCL-PHA의 생산에서 fatty acid pathway로부터 PHA 생합성 전구체 물질들이 만들어진다는 사실과 함께 이에 관여하는 enzymes이 밝혀지고 있다. 본 논문에서는 protein homology search로부터 탐색된 paaG와 ydbU genes의 PHA 생합성에서의 역할을 확인하기 위하여 paaG와 ydbU gene이 각각 knock-out된 mutant E. coli strains 를 제작하였다. 제작된 mutant E. coli들은 모균주들보다 낮은 PHA 농도와 함량을 가졌으며, 이러한 결과들로부터 paaG와 ydbU는 fatty acid pathway에서 PHA synthesis의 전구체 물질들을 공급한다는 사실을 확인하였다. 또한, 새로운 FadB homologous enzyme YgfG를 탐색하였으며, ygfG gene이 overexpression된 균주와 ygfG mutant를 제작하여 PHA 합성을 실험한 결과 ygfG도 paaG와 ydbU와 유사한 역할을 한다는 사실을 밝혔다. 이러한 연구결과들은 E. coli에서의 MCL-PHA 단량체들의 합성 경로를 확인하여 효과적인 PHA 생산 균주를 제작할 수 있게 할 것이다.

• Journal of Microbiology
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• 제42권3호
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• pp.188-193
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• 2004

Xanthobacter flavus strain UE15 was isolated in wastewater obtained from the Ulsan industrial complex, Korea. This strain functions as a 1,2-dichloroethane (1,2-DCA) degrader, via a mechanism of hydrolytic dechlorination, under aerobic conditions. The UE15 strain was also capable of dechlorinating other chloroaliphatics such as 2-chloroacetic acid and 2-chloropropionic acid. The dhlA gene encoding 1,2-DCA dechlorinase was cloned from the genomic DNA of the UE15 strain, and its nucleotide sequence was determined to consist of 933 base pairs. The deduced amino acid sequence of the DhlA dechlorinase exhibited 100％ homology with the corresponding enzyme from X. autotrophicus GJ10, but only 27 to 29％ homology with the corresponding enzymes from Rhodococcus rhodochrous, Pseudomonas pavonaceae, and Mycobacterium sp. strain GP1, which all dechlorinate haloalkane compounds. The UE15 strain has an ORF1 (1,356 bp) downstream from the dhlA gene. The OFR1 shows 99％ amino acid sequence homology with the transposase reported from X. autotrophicus GJ10. The transposase gene was not found in the vicinity of the dhlA in the GJ10 strain, but rather beside the dhlB gene coding for haloacid dechlorinase. The dhlA and dhlB genes were confirmed to be located at separate chromosomal loci in the Xanthobacter flavus UE15 strain as well as in X. autotrophicus GJ10. The dhlA and transposase the UE15 strain were found to be parenthesized by a pair of insertion sequences, 181247, which were also found on both sides of the transposase gene in the GJ10 strain. This unique structure of the dhlA gene organization in X. flavus strain UE15 suggested that the dechlorinase gene, dhlA, is transferred with the help of the transposase gene.

• Journal of Microbiology
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• 제42권3호
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• pp.216-222
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• 2004

In a previous paper, the ogdH gene that encodes 2-oxoglutarat dehydrogenase was isolated from Salmonella typhimurium. The catalytic N-terminal region in the enzyme was found to be very specific for the Salmonella species. Therefore, the aim of the present study was to detect S. typhimurium in food sources using primers designed for OGDH-l and OGDH-2 which were based on the salmonella-specific region of the ogdH gene. A simple polymerase chain reaction (PCR) detection method was developed to detect low numbers of S. typhimurium in a chicken meat microbial consortium. Using the ogdH-specific primers under stringent amplification conditions and for gene probe analysis, fewer than 100 colony-forming units (CFUs) were detectable when pure cultures were employed. When the PCR assay was run on S. typhimurium-contaminated meat contents, only the positive meat samples containing as few as 200 CFUs reacted to the assay. The method employed for sample processing is simple and it was determined to provide a sensitive means of detecting trace amounts of S. typhimurium-specific sequences in the presence of mixed meat microbial populations. When compared with six representative intestinal gram-negative bacterial strains in foods, including Vibrio parahaemolyticus, V. vulnificus, Enterobacter cloacae, E. coli O157:H7, Pseudomonas aeruginosa, and Proteus sp., S. typhimurium had a unique and distinct PCR product (796 bp). In conclusion, the two OGDH primers were found to be rapid and sensitive detectors of Salmonella spp for the PCR method.

• 한국미생물·생명공학회지
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• 제20권6호
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• pp.681-686
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• 1992

D,L-ATC의 L-cysteine으로의 생물학적 전환에 있어 균체를 이용할 때, 계면활성제의 영향, 효소의 안정성 및 연속생산공정중의 고정화 균체 반응기의 안정성에 대하여 분석하였다. 계면활성제의 첨가없이 균체만을 이용할 때 반응은 매우 미미하게 이루어졌으나 SDS와 Triton X-100을 첨가할 때 cell-free 조효소액을 이용하는 경우와 비슷한 정도의 결과가 얻어졌다. 효소 활성은 $30^{\circ}C$에서 7시간 저장후 50 저하되었으며 질소가스하의 혐기적인 조건에서는 활성저하가 거의 일어나지 않았다. 이와 같은 효소의 불활성화는 효소에 대한 산소의 작용으로 사료되었다. 그러나, alginate로 고정화한 균체를 이용한 연속반응공정에서 혐기적으로 조건하에서 150시간 내에 대부분의 활성을 잃어버렸으며, L-cysteine 저해제인 hydroxylamine을 첨가할 때 효소활성이 급속히 감소되었다.

• Journal of Microbiology and Biotechnology
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• 제17권1호
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• pp.52-57
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• 2007

Growth promotion of wild plants by some plant growth-promoting rhizobacteria (PGPR) was examined in the microcosms composed of soils collected separately from a grass-covered site and a nongrass-covered site in a lakeside barren area at Lake Paro, Korea. After sowing the seeds of eight kinds of wild plants and inoculation of several strains of PGPR, the total bacterial number and microbial activity were measured during 5 months of study period, and the plant biomasses grown were compared at the end of the study. Acridine orange direct counts in the inoculated microcosms, $1.3-9.8{\times}10^9\;cells{\cdot}g\;soil^{-1}$ in the soil from the grass-covered area and $0.9-7.2{\times}10^9\;cells{\cdot}g\;soil^{-1}$ in the soil from the nongrass-covered site, were almost twice higher than those in the uninoculated microcosms. The number of Pseudomonas sp., well-known bacteria as PGPR, and the soil dehydrogenase activity were also higher in the inoculated soils than the uninoculated soils. The first germination of sowed seeds in the inoculated microcosm was 5 days earlier than the uninoculated microcosm. Average lengths of all plants grown during the study period were 26% and 29% longer in the inoculated microcosms starting with the grass-covered soil and the nongrass-covered soil, respectively, compared with those in the uninoculated microcosms. Dry weights of whole plants grown were 67-82% higher in the inoculated microcosms than the uninoculated microcosms. Microbial population and activity and growth promoting effect by PGPR were all higher in the soils collected from the grass-covered area than in the nongrass-covered area. The growth enhancement of wild plants seemed to occur by the activities of inoculated microorganisms, and this capability of PGPR may be utilized for rapid revegetation of some barren lands.

• 한국토양비료학회지
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• 제44권2호
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• pp.236-241
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• 2011

경남지역 과수원 토양 25개소를 대상으로 2010년에 토양 화학성분과 미생물 다양성을 검토하고 토성, 지형 및 작물별 주요 변동요인을 주성분분석으로 해석하였다. 토양 유효인산 및 치환성 칼륨 함량은 적정수준 보다 각각 2.6배 및 2.3배 높았으며 대부분 토양 화학성분의 최소값과 최대값 차이가 크게 나타났다. 지형적으로 산록경사지는 토양 유효인산 함량이 유의적으로 높았고 (p<0.05) 미사질양토에서 곰팡이와 형광성 슈도모나스균 개체수가 사양토 보다 유의적으로 높았다 (p<0.05). 주성분 분석결과 제 1주성분이 28.4%, 제 2주성분이 20.1%로서 전체 48.5%의 자료를 설명할 수 있었으며 제 1주성분은 토양의 세균 개체수가 가장 크게 기여하였다. 토양 유기물 함량은 곰팡이 개체수와 정의상관을 보인 반면 세균 개체수와 부의상관을 나타냈다.

• Preventive Nutrition and Food Science
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• 제9권2호
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• pp.138-143
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• 2004

Soybean curd residues (SCR) obtained from hot and cold manufacturing processes were fermented by indigenous microorganisms, Lactobacillus rhamnosus LS and Bacillus firmus NA-l for 15 h at 37$^{\circ}C$. The pH, acidity, viable cell counts, and tyrosine content were evaluated in samples with variations in sugar, starter and type of SCR. The raw Doowon SCR (D-SCR, cold-processed) fermented by indigenous microorganism had a 0.9% acidity and 6.7 ${\times}$ 10$^{7}$ CFU/g viable cell counts, compared with the 0.11 % acidity and 6.7 ${\times}$ 10$^{6}$ CFU/g viable cell counts of raw fermented Pulmuwon SCR (P-SCR, hot-processed). After fermentation of raw P-SCR with 1 % glucose and 1 % L. rhamnosus LS starter, the viable cell counts, tyrosine content and acidity were 4.7 ${\times}$ 10$^{8}$ CFU/g, 16.3 mg% and 0.9%, respectively. In addition, the raw P-SCR fermented with Bacillus firmus NA-l as co-starter had a 0.45% acidity, 2.4 ${\times}$ 10$^{8}$ CFU/g lactic acid bacteria, and 3.3 ${\times}$ 10$^{6}$ CFU/g Bacillus sp. In particular, the tyrosine content was increased 5 fold. The drying of fermented SCR was completed by hot-air drying (5$0^{\circ}C$) within 12 h; the dried P-SCR and D-SCR had 1.8 ${\times}$ 10$^{7}$ CFU/g and 5.3 ${\times}$ 10$^{6}$ CFU/g viable cell counts, respectively. The concentrate of methanol extract from fermented D-SCR inhibited the initial cell growth of E. coli, Staphylococcus aureus and Pseudomonas aeruginosa in liquid culture.

• Journal of Microbiology and Biotechnology
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• 제19권1호
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• pp.42-50
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• 2009

Fifty-four Pectobacterium carotovorum subsp. carotovorum strains isolated in Korea were characterized by a spectrum of antibacterial activities against 7 indicator strains chosen to represent various regions and host plants. All P. carotovorum subsp. carotovorum isolates tested could be grouped into 4 classes depending on the pattern of antibacterial substance production. All tested strains had DNA fragment(s) homologous to the genes encoding carotovoricin and 21 of them had genes homologous to DNA invertase. Sixteen strains had genes homologous to the genes encoding carocin S1. Several isolates produced antibacterial substances active against strains in Brenneria, Pantoea, and Pectobacterium genera that belonged formerly to the genus Erwinia. Strains in Pseudomonas or Xanthomonas sp. were not sensitive to the antibacterial substances produced by P. carotovorum subsp. carotovorum, except for X. albilineans that was sensitive to antibacterial substances produced by most strains in P. carotovorum subsp. carotovorum and P. betavasculorum KACC10056. These results demonstrated the diverse patterns of antibacterial substance production and the possibility of the existence of new antibacterial substance(s) produced by P. carotovorum subsp. carotovorum isolated in Korea.

• Natural Product Sciences
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• 제23권3호
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• pp.151-156
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• 2017

A phytochemical study of Alphonsea cylindrica King (unreported) has led to the isolation of six alkaloids. The compounds were identified as kinabaline (1; azafluorenone alkaloid), muniranine (2), O-methylmoschatoline (3; oxoaporphine alkaloid), lysicamine (4), atherospermidine (5) and N-methylouregidione (6; 4, 5-dioxoaporphine alkaloid). The structures of the isolated compounds were determined based on the spectroscopic techniques and by comparison with data reported in the literature. Alkaloid 2 was isolated as a new derivative of azafluorenone while alkaloids 1, 3 - 6 were isolated for the first time from Alphonsea species. In addition, alkaloid 3 and 4 showed inhibition zone against Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus cereus in disc diffusion test. The minimum inhibition concentration (MIC) values of lysicamine (4) against S. aureus, B. cereus and P. aeruginosa were found to be smaller than O-methylmoschatoline (3). Therefore, the reported antibacterial activity showed the potential of this plant as natural antibacterial agent and supported the documented traditional use of Alphonsea sp. in the treatment of diarrhea and fever.

• 미생물학회지
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• 제29권6호
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• pp.392-396
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• 1991

Pseudomonas sp. DJ77의 chromosomal DNA로부터 6.9kb XhoI 절편 상에 존재하는 phenanthrene 분해에 관련된 유전자군을 vector pBLUESCRIPT SK(+)에 클로닝하였다. 이렇게 얻은 재조합 plasmid인 pHENX7을 가지고 있는 JM101 균주는 3-methylcarechol을 노란색의 meta-cleavage 화합물로 전환할 수 있었다. 그러나 삽입된 절편의 방향이 반대가 되도록 제조한 pHENX7은 extradiol dioxygenase 활성을 나타내지 않기 때문에 전사방향을 알 수 있었다. pHENX7과 이의 듀도체들을 지니는 JH101균주에서 PhnC(24kDa), PhnD(31KDa), PhnE(34kDa), PhnF(KDa)의 4 polypeptide를 확인 할 수 있었고 개개의 유전자의 위치와 범위를 알 수 있었다. 유전자 순서는 phnC-phnD-phnE-phnF-phnG이었으며, phnC, phnD, phnE, phnF, phnG는 각기 glutathione S-transferase, meta-cleavage compound hydrolase extradiol dioxygenase, meta-cleavage compound dehydrogenase의 유전자이었다.