• The Korean Journal of Ecology
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• 제25권5호
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• pp.353-358
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• 2002

소나무과 식물(곰솔, 리기다소나무 및 소나무)이 지닌 monoterpene의 표준시약 12가지를 4가지 농도별로 Escherichia coli와 Aspergillus nidulans에 처리하여 성장 저해 효과를 조사하였다. E. coli의 성장 저해 효과가 있는 것들은 (R)(-)carvone, (S)(+)carvone, (1R)(-)fenchone, (-)menthone, α-pinene, (1S)(-)verbenone 그리고 (+)β-pinene이었고, 이들 중에서 가장 높은 성장 저해 효과를 보이는 것은 (+)β-pinene이었다. 그리고 A. nidulans에 성장 저해 효과를 보이는 것들은 (R)(-)carvone, (S)(+)carvone, (+)β-pinene, geranyl-acetate, α-pinene 그리고 (1S)(-)verbenone이었다. 본 실험에서 A. nidulans에 성 장 저해 효과를 나타내는 monoterpene은 대부분 E. coli에서도 저해효과를 보이는데, 다만 geranyl-acetate는 E. coli에서는 전혀 영향을 미치지 않는 것으로 나타났다. 또한 (1R)(-)fenchone과 (-)menthone은 E. coli의 성장 억제를 하는 반면. A. nidulans의 성장에는 영향이 없었다. 특히 주목할 만한 점은 myrcene, sabinene, bornyl acetate 그리고 limonene의 경우 두 종 모두에서 성장 저해 효과가 전혀 나타나지 않았다.

• 한국동물위생학회지
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• 제15권1호
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• pp.26-31
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• 1992

The oil emulsion and alhydrogel vaccines were prepared from a strain of enterotoxigenic Escherichia coli isolated from calves with diarrhea and their protective efficacy and immunogenicity were tested in Guinea-pigs. Enterotoxigenic Escherichia coli, isolated from calves with diarrhea, has K99 and F4l antigen as 46.2％ and 50.9％ with 48 and 53 strains respectively out of 104 strains. The protective efficacy of the gel and oil vaccines were 60% and 80% respectively. Agglutinin titers to sera of Guinea-pigs vaccinated with experimental gel and oil vaccines peaked at 5 and 6 weeks after vaccination.

• Archives of Pharmacal Research
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• 제19권5호
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• pp.353-358
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• 1996

E. coli 11 and E. coli 101, clinical isolates of Escherichia coli were resistant to various quinolones, especially MICs to norfloxacin of both strains were higher than 100 mg/ml. In the presence of carbonyl cyanide m-chlorophenylhydrazone, a proton gradient uncoupler, norfloxacin uptake in both strains was increased, suggesting that an efflux system play an important role in the norfloxacin resistance. Outer membrane proteins of the susceptible and resistant strains which could affect the route of norfloxacin entry into cells were different. When quinolone resistance determining region(QRDR) of gyrA was amplified using PCR and cut with Hinf I, QRDR in the susceptible strain yielded two fragments while QRDRs in E. coli 11 and E. coli 101 yielded only one uncut fragment. When DNA sequence of QRDR was analyzed, there were two mutations as Ser-83 and Asp-87 in both resistant strains. these residues were changed to Leu-83 and Asn-87, respectively. These results showed that the norfloxacin resistance of E. coli 11 and E. coli 101 was resulted from multiple changes-an altered DNA gyrase A subunit, a change in route of drug entry, and reduction in quinolone concentration inside cells due to an efflux system.

• 한국미생물·생명공학회지
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• 제15권5호
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• pp.346-351
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• 1987

Clostridium thermocellum의 cellulase 유전자를 pBR322를 이용하여 Escherichia coli에 cloning하였다. 삽입된 Hind III 분해 DNA 단편의 크기는 약 1. 8kb였으며 이미 알려진 C. themocellum의 cellulase gene과는 다른 제한효소 분해위치를 가진 새로운 cellulase gene으로서 E, coli에서 CMCase와 FPase 활성을 나타내었다. 이 유전자는 생육의 전시기를 통해 표현되었고 고온성 cellulase의 구조적, 기능적 특성이 그대로 유지되었을 뿐만 아니라 상당량이 세포밖으로 분비되었다.

• Fisheries and Aquatic Sciences
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• 제6권1호
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• pp.20-26
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• 2003

A bacterial strain was isolated from seawater to screen for phytase activities. A colony had the highest activity and was identified as an Escherichia coli strain. Using primers derived from E. coli acid phosphatase appA sequence, we cloned a 1,495 bp DNA fragment connected with the pGEM-T vector. It was over-expressed under lac promoter combined with its native promoter in E. coli $DH5\alpha$. The expression of the phytase gene occurred during late exponential growth and the intracellular phytase production was 16.9 units/ml. The yield of recombinant phytate was 412-fold higher than that of wild type E. coli K13.

• 대한수의학회지
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• 제17권1호
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• pp.5-8
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• 1977

One hundred and fifty seven Escherichia coli strains isolated from 18 cattle (9 dairy cattle received penicillin, streptomycin (SM) or sulfadimethoxine for treatment of diseases and 9 Korean native cattle not received antibiotics) were studied for the drug resistance and distribution of R factors. Of 88 E. coli strains isolated from cattle not received antibiotics, only 1 strain was resistant to SM, but about 46 per cent of 69 E. coli strains isolated from cattle received antibiotics were resistant to SM, tetracycline (TC), ampicillin (AP), kanamycin (KM), chloramphenicol (CM), and sulfisomidine (Su), alone or in combination thereof. Of resistant strains, about 72% were resistant to three or more antibiotics, but 28% were found to singly resistant. The most frequent resistant pattern was triple resistance to AP, KM and Su (37.6%), and quadruple one to SM, TC, CM and Su (12.5%). About 28% of resistant strains carried R factors which were transferable to E. coli ML 1410 $NA^r$ by conjugation.

• 대한가정학회지
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• 제37권4호
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• pp.29-40
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• 1999

Effects of the commercial laundry detergents, fabric softeners, and bleaches on bactericidal activities were studied. Bactericidal activities under various conditions during washing, rinsing, and bleaching were evaluated in terms of minimum inhibitory concentration(MIC) by a broth dilution method. The experiments were carried out using Staphylococcus aureus and Escherichia coli which were usually employed in antibacterial activity tests. The results are summarized as follows : 1. All samples of Powder detergents(10 samples), soaps(7 samples) and fabric softeners(4 samples) were inactive against the Staphylococcus aureus and Escherichia coli. 2. One sample in the liquid detergents(6 samples) showed a very low MIC for Staphylococcus aureus and Escherichia coli., and three samples showed a selective effect for two bacterial strains. 3. Bleaching agent(containing peroxide) did not have bactericidal effect for Staphylococcus aureus and Escherichia coli. but the other(containing chlorine) had the effect for every bacterial strain in standard concentration. 4. All samples showed bactericidal effect above 60$^{\circ}C$.

• 한국식품영양학회지
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• 제12권2호
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• pp.184-190
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• 1999

Soybean protein consists of two major components $\beta$-conglycinin and glycinin which together consti-tute 70% of the total seed storage protein at maturity. $\beta$-Conglycinin is trimeric glycoprotein and for-med by the assembly of various combinations of three subunits $\alpha$,$\alpha$' and $\beta$ which have molecular weig-hts of 69,000, 72,000 and 42,000, respectively. Recently $\beta$-conglycinin was identified as powerful LDL lip-oprotein receptor activation hypercholesterolemia and major allergenic proteins. To investigate these reasons we constructed an expression system of cDNA encoding $\alpha$-subunit of $\beta$-conglycinin in Escherichia coli and purified the expressed protein. The pro-$\beta$-conglycinin synthesized in Escherichia coli BL 21 (DE3)comprised approximately 15% of the total bacterial proteins and the expressed protein are formed sol-uble and trimer such as native protein in Escherichia coli cells. The highly expressed protein was purified to homogeneity by salt precipitation with 20~40 % ammonium sulfate ion-exchange chromatography with Q-sepharose and hydrophobic column chromatography with Butyltoyopearl.

• 한국식품영양과학회지
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• 제30권1호
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• pp.196-198
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• 2001

The growth retardation of Escherichia coli and Staphylococcus aureus by heat or acid treated leek (Allium tuberosum) extract was observed. Antimicrobial activity of the leek was the most effective when fresh leek extract was used, but it was stable after heat treatment at 68$^{\circ}C$ for 30 min or 98$^{\circ}C$ for 20 min. It was also relatively stable after incubated at pH 2.0 for 3 hrs. The antimicrobial activity in leek was not detected after dialysis with molecular weight cutoff of 12,000. Therefore it seems to be small molecule with molecular weight lower than 12,000.

• KSBB Journal
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• 제27권2호
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• pp.127-130
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• 2012

In this study, the effects of pH, temperature, IPTG concentration and substrate (MSG) concentration on gamma-aminobutyric acid (GABA) production in engineered Escherichia coli were investigated. Glutamate decarboxylase and glutamate/GABA antiporter were overexpressed in GABA aminotransferase knock-out strain for GABA production. The result of optimization study showed the GABA bioconversion was optimized at pH 3.5, $30^{\circ}C$, 0.5 mM IPTG, 10 g/L MSG. At this condition, 5.23 g/L of final GABA concentration of was achieved from 10 g/L of MSG, which corresponded to a GABA yield of 85.77%.