• 한국축산식품학회지
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• 제30권1호
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• pp.148-153
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• 2010

시중에서 판매되는 계육과 돈육 가검물 1085개를 구입하고, 총 217개의 대장균 분리주를 확보하였다. 현재 알려진 대장균 병원성 인자 11개(astA, elt, estI, estII, cdt, cnf, eae, afa, stx, inve, aggR)의 보유여부를 PCR 기법으로 조사하였다. 돈육유래 대장균에서 존재하는 병원성 인자는 astA(6.9%), eae와 elt(4.6%), estII(4.0%), estI(2.3%), afa (1.1%), cnf(0.6%)의 순으로 검출되었으나, cdt, stx, aggR, inve는 검출되지 않았다. 계육에서 분리된 대장균 42개 중에서 astA와 inve를 보유하고 있는 병원성 대장균이 각각 1개씩 확인되었다. 특히 astA는 돈육과 계육에서 분리된 대장균 중에서 높은 빈도로 존재하고 있음을 확인하였으며, cnf와 afa같이 기존에 알려지지 않은 병원성 인자들의 존재도 확인되었다.

• 한국식품과학회지
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• 제35권4호
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• pp.752-755
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• 2003

E. coli O157:H7에 대한 마늘즙액의 항균작용을 알아보기 위하여 마늘즙액의 처리량을 농도별 조건을 달리한 후 생균수 측정을 실시하였다. 마늘즙액 농도가 1%에서는 첨가하지 않았을 때에 비해 E. coli O157:H7의 생균수가 약간 줄어들었으나 마늘즙 처리량이 3%에서는 약 5 log, 마늘즙 처리량이 5%로 증가했을 때는 약 6 log의 생균수 감소를 보였다. 마늘즙의 식육내 항균작용 효과를 알아본 결과, 저육에서 3%, 6%, 10%의 마늘즙 농도별 차이에 따른 E. coli O157:H7에 대한 항균효과는 크게 다르지 않음을 알 수 있었다. 마늘즙의 가장 뚜렷한 저해 효과는 저장 9일에 나타나 약 2 log의 생균수 감소가 관찰되었다. 저장 9일 이후에는 E. coli O157:H7의 생균수가 다시 증가하는 것으로 미루어 마늘즙의 항균 효과가 소실되는 것으로 추정된다. 본 실험의 결과, 마늘의 조미료로써의 기능과 더불어 천연 방부제로써의 항균효과에 관한 기초 자료를 얻을 수 있었다.

• 한국미생물·생명공학회지
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• 제23권4호
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• pp.454-460
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• 1995

Acetylxylan esterase II was produced by Escherichia coli HB101 harboring the recombinant plasmid pKMG7 which contained the estII gene of Bacillus stearothermophilus. Optimal medium for the production of the acetylxylan esterase by E. coli HB101/pKMG7 was determined to contain 0.5% galactose, 1% yeast extract and 1% NaCl. The enzyme produced was purified to homogeneity using a combination of 20-50% ammonium sulfate precipitation, DEAE-Sepharose CL-6B chromatography and Sephacryl S-200 gel filtration. The temperature and pH optimum of the esterase were 45$\circ$C and pH 6, respectively. The essential amino acids for the esterase activity were found to be methionine, serine, and cysteine. Molecular weight of the esterase was determined to be 28 kDa by SDS-polyacrylamide gel electrophoresis, and 120 kDa by gel filtration. This suggests that the functional enzyme is a homomeric tetramer. The esterase had an isoelectric point of pH 3.4. The N-terminal amino acid sequence of the enzyme was Ala-Leu-Phe-Glu-Ser-Arg-Phe-Phe-Ser-Glu-Val-Leu-Gly-Leu.

• Journal of Microbiology
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• 제38권1호
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• pp.36-39
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• 2000

Toxic hexavalent chromium, Cr(VI), was reduced to a less toxic trivalent chromium form by E. coli ATCC 33456. The suitable electron donor for Cr(VI) reduction was glucose. E. coli ATCC 33456 was more resistant to metal cations than other reported Cr(VI) reducing microorganisms. Cell growth was inhibited by the presence of Cr(VI) in a liquid medium and Cr(VI) reduction accompanied cell growth. With a hydraulic retention time of 20 h, Cr(VI) reducing efficiency was 100% to 84% when Cr(VI) concentration in the influent was in the range of 10 to 40 mg L$\^$-1/. Specific rate of Cr(VI) reduction was 2.41 mg Cr(VI) g DCW$\^$-1/ h$\^$-1/ when 40 mg L$\^$-1/ of Cr(VI) influent was used. This result suggested the potential application of E. coli ATCC 33456 for the detoxification of Cr(VI) in Cr(VI) contaminated wastewater.

• 약학회지
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• 제42권1호
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• pp.12-24
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• 1998

For the development of new cephalosporin antibiotics with aminothiazolcarboxymethylethoxyimino moiety on the C-7 position and tetrazolymethyl moiety on the C-3 position of cephe m ring, 7${\beta}$-[(Z)-2-(2-aminothiazol-4-yl)-2-(1-carboxy-1-methylethoxyimino)acetamido]-3-[5-(substituted)tetrazol-2-yl]methyl-3-cephem-4-carboxylic acids(28-35) were synthesized. These compounds were tested for antimicrobial activity in vitro against Gram(+) and Gram(-) bacteria. They showed remarkable antibacterial activity against Escherichia coli AB 1157, Escherichia coli AB 0111, Escherichia coli BE 1186, Micrococcus luteus ATCC 9341, Salmonella typhimurium TV 119, Salmonella typhimurium SL 1102, Staphylococcus aureus IFO 12732, Staphylococcus aureus R-209, but these compounds were not active against Pseudomonas aeruginosa N-10.

• Bulletin of the Korean Chemical Society
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• 제28권2호
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• pp.257-262
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• 2007

The efficient synthesis of a tetrasaccharide, the suitably protected form of the repeat unit, →2)-α-D-Manp-(1→2)-β-D-Manp-(1→3)-α-D-GlcpNAc-(1→6)-α-D-Manp-(1→, of the O-antigen polysaccharide of the lipopolysaccharide from E. coli O77 has been accomplished. Glycosylation reactions for the coupling of four monosaccharide building blocks of the tetrasaccharide were carried out employing the CB glycoside method, the mannosyl 4-pentenoate/PhSeOTf method, and the glycosyl trichloroacetimidate method with complete stereoselectivities in excellent yields.

• Journal of Microbiology and Biotechnology
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• 제17권9호
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• pp.1579-1584
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• 2007

5-Aminolevulinate (ALA) synthase (E.C. 2.3.1.37), which mediates the pyridoxal phosphate-dependent condensation of glycine and succinyl-CoA, encoded by the Rhodobacter sphaeroides hemA gene, enables Escherichia coli strains to produce ALA at a low level. To study the effect of the enhanced C4 metabolism of E. coli on ALA biosynthesis, NADP-dependent malic enzyme (maeB, E.C. 1.1.1.40) was coexpressed with ALA synthase in E. coli. The concentration of ALA was two times greater in cells coexpressing maeB and hemA than in cells expressing hemA alone under anaerobic conditions with medium containing glucose and glycine. Enhanced ALA synthase activity via coupled expression of hemA and maeB may lead to metabolic engineering of E. coli capable of large-scale ALA production.

• 한국미생물·생명공학회지
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• 제34권1호
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• pp.35-39
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• 2006

높은 C4 대사활성을 보이는 반추위미생물이 가지는 포도당 발효대사 조절양식의 한가지를 대장균에서 모사하였다. 대장균은 glycolytic condition에서는 phosphoenolpyruvate(PEP) ${\leftrightarrow}$ oxaloacetate(OAA)간 반응을 phosphenolpyruvate carboxylase(PPC)에 의해, gluconeogenetic condition에서는 phosphoenolpyruvate carboxykinase(PCK)에 의해 촉매하도록 조절한다. 반면 반추위미생물은 glycolytic condition에서 PCK를 통하여 반응이 촉매된다. 이러한 조절양식의 차이점이 C4 대사활성에 미치는 영향을 조사하기 위하며 ppc가 돌연변이되고 대신 인위적으로 PCK를 발현할 수 있는 대장균을 제조하였다. 이렇게 PEP-OAA간 대사조절이 변이된 대장균 K12 ppc-/pck+는 야생형 K12보다 2.5배의 높은 C4대사활성을 보였다. 대장균에서의 C4 대사생리를 증가시키는 연구는 대사공학을 이용한 여러가지 유용물질(i.e. 숙신산, ALA)생산에 응용하기 위한 기초자료로 활용될 수 있을 것으로 기대된다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권4호
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• pp.353-356
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• 2005

The effect of silkworm hemolymph on the expression of recombinant protein in Escherichia coli was investigated. The addition of silkworm hemolymph to the culture medium in­creased the production of recombinant $\beta$-galactosidase in E. coli. The production was dependent on the concentration of the added silkworm hemolymph, which increased 2-, 5-, and 8-fold in media supplemented with 1, 3, and $5\%$ silkworm hemolymph, respectively. To identify the effective component, the silkworm hemolymph was fractionated by gel filtration column chromatography. A fraction, with a molecular weight of about 30 K was identified as the effective component.

• Journal of Microbiology and Biotechnology
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• 제2권1호
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• pp.50-55
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• 1992

A genomic library of a mesophilic cellulolytic anaerobe, Clostridium sp. KCTC 8440 DNA was constructed in Escherichia coli using plasmid pUC9. Clones of E. coli exhibiting carboxymethyl cellulose-hydrolyzing activity (CMCase) were isolated and divided into seven types based on the restriction enzyme patterns of recombinant plasmids. E. coli strains carrying type A genes showed activity on carboxymethyl cellulose about 7-8 times greater than clones carrying genes of other types. Restriction maps of the cloned DNA fragments were determined, and homologies between them were investigated. The results suggest that Clostridium sp. KCTC 8440 has seven distinct CMCase genes.