• The Korean Journal of Mycology
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• v.32 no.2
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• pp.145-147
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• 2004

The ethyl acetate extracts from the liquid cultures of Coriolus versicolor, Phellinus linteus, and Hericium erinaceus showed significant antibacterial activities against Escherichia coli K88, E. coli K99, E. coli 987P, and Salmonella typhimurium 14058 causing bacterial diarrhea in Korean house pigs and chicken. Of these extracts, Coriolus versicolor extract showed the highest antibacterial activity. In addition, these extracts also showed significant growth inhibition against Staphylococcus aureus CARM3230 and E. coli CARM1381 which are known as kanamycin and ampicillin-resistant strains. These results showed that the mushroom extracts could be developed as a livestock feed additives that can replace commercial antibiotics, and also could be good resources for the development of a new antibacterial agent.

• Applied Biological Chemistry
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• v.39 no.5
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• pp.343-348
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• 1996

Experiments were carried out to find possibility of economic production of SCP in mixed culture by Cellulomonas sp. KL-6 and E. coli LI-10. The best cell growth was obtained at the ratio of 1 : 1(v/v) in mixed culture. When these strains were mixed culture, cell growth was increased to about 63%, compared with those of single culture of strain KL-6. It was found that the majority of the population during growth in mixed culture consisted of strain KL-6. $CaCO_3$ added to the medium as the ratio of 0.1% was enhanced medium pH. Cell growth increased in that circumstances. These strains produced much amounts of cellobiose, but glucose was not detected in filter paper medium. When these organisms were cultured under the optimal medium for 4 days, cell mass was produced $1.0\;g/{\ell}$. The results showed the increase of cell mass up to 53% than those produced in CMC medium.

• Journal of Microbiology and Biotechnology
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• v.12 no.5
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• pp.753-759
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• 2002

$\beta$-Cyclodextrin glucanotransferase ($\beta$-CGTase) was overproduced extracellularly using recombinant E. coli by transforming the plasmid pECGT harboring a secretive signal peptide. The $\beta$-CGTase gene of alkalophilic Bacillus firmus var alkalophilus was inserted into the high expression vector pET20b(+) containing a secretive pelB signal peptide, and then transformed into E. coli BL2l(DE3)pLysS. The optimum culture conditions fer the overproduction of $\beta$-CGTase were determined to be TB medium containing 0.5% (w/v) soluble starch at post-induction temperature of $25^{\circ}C$. A significant amount of $\beta$-CGTase, up to 5.83 U/ml, which was nine times higher than that in the parent strain B. firmus var. alkalophilus, was overproduced in the extracellular compartment. A pH-stat fed-batch cultivation of the recombinant E. coli was also performed to achieve the secretive overproduction of $\beta$-CGTase at a high cell density, resulting in production of up to 21.6 U/ml of $\beta$-CGTase.

• Applied Biological Chemistry
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• v.46 no.3
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• pp.171-175
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• 2003

The putative endochitinase gene, yheB of Escherichia coli K-12 is not expressed under lab culture conditions. The endochitinase gene was amplified by PCR and subcloned into pET28c vector and pQE9 vector, respectively. The endochitinase produced in E. coli harboring pET28c containing yheB or pQE9 vector containing yheE was partly released into the growth medium. The overproduced endochitinase was partially purified by His affinity column chromatography and DE-52 column chromatography. The apparent molecular weight of the endochitinase determined by SDS-polyacrylamide gel electrophoresis was about 97,000. The purified E. coli endochitinase showed maximal chitinolytic activity at pH 6 and $40^{\circ}C$.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.711-714
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• 2001

The production of the recombinant Plasmodium vivax merozoite surface protein (PvMSP) has been investigated in the recombinant E.coli system. Experimental optimization of the culture conditions, such as the effect of initial pH, and operating temperature has been tried on the growth of recombinant E.coli and on the overproduction of the target foreign protein.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.1082-1084
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• 2007

Ultra-high temperature (UHT) processed full fat milk inoculated with Escherichia coli, Pseudomonas fluorescens, and Bacillus stearothermophilus was exposed to 30-60 kV/cm square wave pulsed electric field (PEF) with $1\;{\mu}sec$ pulse width, and $26-210\;{\mu}sec$ treatment time in a continuous PEF treatment system. Eight log reduction was obtained for E. coli and P. fluorescens and 3 logs reduced for B. stearothermophilus under PEF treatment conditions of $210\;{\mu}sec$ treatment time, 60 kV/cm pulse intensity at $50^{\circ}$. There was no significant change in pH and titration acidity of milk after PEF treatment. The electrical energy required to achieve 8 log reduction for E. coli and P. fluorescens was estimated to be about 0.74 kJ/L.

• Archives of Pharmacal Research
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• v.28 no.4
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• pp.433-437
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• 2005

Human cytochromes P450 (GYP) 2A6 and 2E1 are of great interest because of their important roles in the oxidation of numerous drugs and carcinogens. Bacterial expression systems, especially Escherichia coli cells, have been widely used for the production of various GYP enzymes in order to obtain high yield of proteins. The expression methods usually employ longer culture time (30-72 h) at lower temperature (usually under $30^{\circ}C$). Expression levels of GYPs 2A6 and 2E1 at $37^{\circ}C$ were compared to those at $28^{\circ}C$, which is a usual temperature used in most bacterial expression systems for human GYP expression. Within 18 h the expression levels of GYPs 2A6 and 2E1 reached up to 360 and 560 nmol per liter culture at $37^{\circ}C$, respectively, which are compatible with those of 36 h culture at $28^{\circ}C$. The activities of GYPs expressed at $37^{\circ}C$ were also comparable to those expressed at $28^{\circ}C$. The present over-expression system can be useful for rapid production of large amounts of active human GYPs 2A6 and 2E1 in E. coli.

• Journal of Food Hygiene and Safety
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• v.6 no.3
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• pp.147-155
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• 1991

Enterotoxigenic E. coli is one of the major causative agents of the infantile diarrhea and traveler's diarrhea. The heat-stable enterotoxin(ST) is thought to be a virulence factor in the pathogenesis of the diarrhea and to be a maker for identification of the enterotoxingeic E. coli from non pathogenic E. coli. The isolate of enterotoxigenlc E. coli was isolated from swine during 1989 year(from 5 to 10 month) in the Kyong-gi and Chung-Cheong provinces, and three strains(KM-4, KM-7 and KM-12) was selected from 189 isolates of ST producing E. coli. The detection of a ST produced of the isolated E. coli was performed by the infant mouse assay(IMA). This study was designed to know optimal conditions for the production of the ST and the molecular properties of plasmids of the enterotoxigenic E. coli. Amount of ST produced were the most at initial pH 8.5~9.0 of succinate salts medium culture. The cultural time of the same medium was accumulated the highest level of ST was at the 14 to 16 hours, and then stationary phase was at the 20 hours. From this experiment the KM-7 strain was selected among ST producing strains by IMA. Partial plasmid-curing experiment was done to select plasmid encoding for ST among other plasmids and then comparing the plasmid pattern of ST producing strain(KM-7) with those of other ST non-producing strains, it is found that ST gene exists on the about 80 Kbp plasmid. Each fragment of this plasmid digested with EcoRl was ligated to vector pBR 322 and transformed into E. coli K-12. A clone producing ST(eKT 53) was selected by IMA. The EcoRl digestion pattern of the isolated plasmid(pKD 37) from the ST producing clone it is indicated that the size of the inserted fragment in eKT 53 strain is 16 Kbp. The cultured supernatant of eKT 53 strain was positive result of ST production in IMA.

• Korean Journal of Veterinary Research
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• v.38 no.4
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• pp.745-750
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• 1998

A sensitive and rapid enzyme immunoassay(EIA) to detect Escherichia coli O157 in ground beef was developed by using a sandwich type assay with polyclonal antibodies to E coli O157. E coli O157 in ground beef could be detected within 15hr, including incubation for 12hr in enrichment broth and 3hr in immunoassay. The EIA could detect $1.3{\times}10^5$ cells of E coli O157/g of ground beef without enrichment. The lowest limit of detection was 0.23 E coli O157 per g of meat after enrichment. Confirmation was required in the positive specimens in the EIA by culture method even though the negative specimens were not. These results suggested that the immunoassay could be a very efficient method for the screening E coli O157 in meat.

• Journal of Life Science
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• v.14 no.1
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• pp.121-125
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• 2004

The synergistic effect of lowered incubation temperature and CroEL/ES expression on the production of soluble form of B. macerans cyclodextrin glucanotransferase (CGTase) was studied in recombinant E. coli. pTCGTl and pGroll carrying the cgt and groEL/ES genes under the control of T7 promoter and pzt-I promoter, respectively, were co-introduced. Tetracycline (10 ng/ml) and IPTG (1 mM) were added at the early-exponential phase (2 hr) and mid-exponential phase (3 hr). Low temperature cultivation at $25^{\circ}C$ with groEL/ES expression improved the activity of CGTase by two fold, compared to $37^{\circ}C$ cultivation without chaperones. SDS-PACE analysis revealed that about 69% of CGTase in the total CGTase protein was found in the soluble fraction by overexpression of GroEL/ES and cultivation at$25^{\circ}C$, whereas 20% of CGTase was detected in the soluble fraction when E. coli was cultivated at $37^{\circ}C$ without chaperone. The amount of soluble CGTase from $25^{\circ}C$ culture with chaperone was 3.5-fold higher than that of $37^{\circ}C$ culture without chaperone. Therefore the expression of CroEL/ES and low temperature cultivation greatly enhanced the soluble production of CGTase in E. coli.