• The Korean Journal of Food And Nutrition
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• v.6 no.3
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• pp.169-177
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• 1993

The conversion of glutamate by glutamine synthetase Is the endergonic reaction that demands ATP as its energy source. In order to supply efficiently ATP that is demanded in the conversion of glutamate to glutamine, the ATP- generating system by acetate kinase partially purified from Escherichia coli K-12 was coupled with glutamine synthetase partially purified 5. coli K-12 Pgln6. The optinum conditions of the coupled reaction were investigated. As the result, the highest conversion of glutamate to glutamine was shown In the reaction mixture containing 100mM glutamate, 100mM NHtCl, 50M acetyl phosphate, 5mM ADP, 40M MgCl2, 300mM potassium phosphate buffer (pH 7.5), 5mM MnCl2, Under this condition, the most effective concentrations of enzyme were 70unit/ml glutamine synthetase and 99unit/ml acetate kinase. Under the optinum conditions, 98% of 100mM glutamate was converted to glutamine within 6 hours.

• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.44-49
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• 1998

The antimicrobial effects of HAp and Ag-HAp was observed using periprosthetic infection bacteria such as Pseudomonas Aeruginosa, Staphylococcus Epidermidis, Escherichia coli (DH5$\alpha$). Ag-HAp showed good antimicrobial effects. TEM study of E. coli with and without Ag treatment in HAp was experimented in order to find the mechanism of Ag in antimicrobial effects. It was observed that the shape of Ag-treated E. coli was changed, the cells walls became inhomogeneous. The vaculoes at cytoplasm formed into E. coli and finally it was discovered by EDAX that there were many dark granules which contain the Ag element inside the cells.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.188-193
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• 1989

Gene for lactose catabolism in Lactobacillus casei SW-M1 was encoded by a 60Kb metabolic plasmid. A derivative of only 10kb, pPlac 15 of recombinant plasmid, was constructed by introducing into pBR322 and was cloned into E. coli using restriction endonuclease Pst I. A 10kb insery DNA in plasmid pBR322 was identified as a gene encoded phospho-$\beta$-galactosidase by the determination of enzyme activity. Phospho-$\beta$-galactosidase was apparently expressed in E. coli. The enzyme activities of cell-free extract from transformant E. coli HB101 carrying pPLac 15 DNA were not different from that of L. casei as a donor strain on the basis of enzyme properites. However, specific activity of phospho-$\beta$-galactosidase in the cloned strain with Lac $Y^{-}$ phenotype of E. coli HB101 was lower than that in L. casei strain.

• YAKHAK HOEJI
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• v.33 no.2
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• pp.73-79
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• 1989

One hundred and sixteen strains of E. coli isolated from drainage in Seoul city in 1987 and 104 strains of E. coli isolated from stools of domestic animals in suburb of Seoul in 1987 were examined for susceptibilities to 10 antimicrobial agents by the agar dilution method. The susceptibilities of the two groups to each antimicrobial agent were compared and correlations in the antimicrobial susceptibility of the 220 strains of E. coli among the 10 antimicrobial agents were also analyzed. The frequency of resistance strains was highest to tetracycline with 77%, and followed by chloramphenicol, streptomycin, ampicillin, kanamycin and cephalosporin in the descreasing order, tanging from 62% to 10%. Strains resistant to tobramycin, nalidixic acid, gentamicin and amikacin occupied 3 strains, 2 strains, 2 strains and 1 strain respectively.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.1
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• pp.6-10
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• 1998

A plasmid vector containing two reporter genes, mer-lux and lac-GFP, was transformed to both Escherichia coli and Pseudomonas putida. Their cellular activities and biofilm characteristics were investigated in flow-cell units by measuring bioluminescent lights and fluorescent levels of GFP. Bioluminescence was effective to monitor temporal cell activities, whereas fluorescent level of GFP was useful to indicate the overall cell activities during biofilm development. The light production rates of E. coli and P. putida cultures were dependent upon concentrations of HgCl2. Mercury molecules entrapped in P. putida biofilms were hardly washed out in comparison with those in E. coli biofilms, indicating that P. putida biofilms may have higher affinity to mercury molecules than E. coli biofilms. It was observed that P. putida expressed GFP cDNA in biofilms but not in liquid cultures. This may indicate that the genetic mechanisms of P. putida were favorably altered in biofilm conditions to make a foreign gene expression possible.

• Microbiology and Biotechnology Letters
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• v.13 no.3
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• pp.209-212
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• 1985

The cell density and packing characteristics of Escherichia coli immobilized in a dual hollow fiber bioreactor consisting of outer silicone membrane for oxygen transport and three inner isotropic polypropylene hollow fibers for substrate transport were investigated. The cells have grown forming the layer like animal tissue in a nearly 100％ packing density. The dry biomass density was 550g/liter of void volume for cell growth, which was the highest among the biomass densities ever reported.

• Korean Journal of Microbiology
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• v.25 no.4
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• pp.262-273
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• 1987

The replication region of the chloramphenical resistance plasmid pSBK203 of Staphylococcus aureus was cloned using pBR322 and pBD9 as vectors. Cloned replication tegion and chloramphenicol resistance gene were recombined to pBR322. The reconstructed vector behaved as a shuttle vector for E. coli and B. subtilis.

• Fisheries and Aquatic Sciences
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• v.9 no.2
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• pp.97-100
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• 2006

To determine whether the tetracycline resistance genes tet (34), tet (M), and tet (S) can be transferred among bacteria, we used a filter mating experiment allowing intimate cell-cell contact between donor and recipient. The tet(34) gene, conveyed on a chromosome of Vibrio species (No. 6 and SW-42) was not transferred to Escherichia coli JM109, suggesting that it is not transferred among bacterial species. The tet (M) gene was transferred from three Vibrio strains (4-E, SW-18, and SW-38) to E. coli at frequencies of $8.5{\times}10^{-5}\;to\;2.1{\times}10^{-6}$. The tet(S) gene was transferred from Lactococcus garvieae KHS98032 to E. coli at a frequency of $1.8{\times}10^{-6}$. Transconjugated recipients showed increased minimum inhibitory concentrations against oxytetracycline. Although the donors possess the Tn916-Tn1545 transposons, they were not detected in transformed recipients, suggesting that the transfer of tet(M) and tet(S) is mediated by elements or mechanisms. Two ribosomal protect protein genes were also transmissible from marine bacteria to E. coli, suggesting gene hopping among marine, terrestrial, and human environments.

• Journal of Microbiology and Biotechnology
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• v.11 no.4
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• pp.720-723
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• 2001

The effect of long-term storage on garlic antibacterial activity was investigated. A concentration of 5% or more garlic was found to be necessary to completely inhibit Eschrichia coli growth in tryptic soy broth. This value is substantially higher than the minimum inhibitory concentration of 1% for E. coli reported previously. pH-modified garlic extract was stored at different temperatures to investigate the impact of storage conditions (i.e., temperature, pH, period of storage) on the stability of the antibacterial activity of the garlic extract used against E. coli B34. The antibacterial effectiveness of the garlic extract against E. coli remained stable when both the storage temperature and the pH of the extract were kept low. When the garlic extract was stored at $40^{\circ}C and above, most or all of the garlic antibacterial activity disappeared after a 24-h storage period, regardless of the storage pH. The antibacterial activity was weakened when the pH of the garlic extract was adjusted to 8, and at low temperatures.

• Biotechnology and Bioprocess Engineering:BBE
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• v.4 no.1
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• pp.63-65
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• 1999

Although many pharmaceutically useful proteins are produced in E. coli expression system, it is very are rare for the system to be used in the production of diagnostic antigen due to a major problem, i.e., false-positive reaction of e. coli host-derived proteins contaminating purified diagnostic antigen with human sera. The N (nucleocapsid) protein of Seoul virus causing haemorrhagic fever with renal syndrome (HFRS) was produced in E. coli BL21 (DE3), and used for the detection of N protein-specific antibodies in human sera. Using the N protein as a diagnostic antigen of HFRS, the false-positive reaction was cleared by merely mixing the test sera with the extract of E. coli host strain not harboring expression plasmid.