• Korean Journal of Veterinary Service
• /
• v.14 no.2
• /
• pp.127-133
• /
• 1991

The present study was conducted to investigate the biochemical properties, pathogenicity, antimicrobial test, and serotype of E-coli isolated from slaughtered cattle during the period from March 1991 to May 1991. 1. A total of 12 E-coli isolates were isolated from 132 bile juice of slaughtered cattle. 2. All isolates were resistant to Erythromycin, Cephalothin, Neomycin and Lincomycin while the majority of them were susceptible to Trimethoprimsulfamethoxazol (67%), Chloramphenicol(58％), Gentamicin(58%), Ampicillin(17%), Kanamycin(9%) and Tetracycline (9%). 3. In the test of colicinogenecity and congo-red binding capability, 4(33%) isolates produced colicin, all isolates were congo-red negative. 4. The serotypes of isolated E-coli were identified as 008： K- (2 strain), 015： K- (1 strain), 08： K87： K88ab(1 strain), 0139： Kl2(1 strain), 0147: K89(1 strain), others(6 strains ) were autoagglutination.

• Korean Journal of Microbiology
• /
• v.26 no.2
• /
• pp.113-121
• /
• 1988

Ozone, an atmospheric pollutant, can damage similar UV and X-rays DNA and its components. It is possible then that the KNA damage produced by this gas are similar, to some extent, to those of radiations and that they could be repaired by the same DNA repair mechanisms. It has been observed in Escherichia coli that radiosensitive strains such as lex A, rec A and pol A, all deficient to some extent for DNA repair, are more sensitive to ozone than a wild type strain. We have thendetermined the ozone resistance and host-cell reactivation of ozone-damaged T3 phages for the E. coli double mutants pol A, lex A, uvr B, lex A, uvr A, rec A and rec A lox A. According to the results, the DNA polymerase 1 plays a key role in ozone resistance and Type 11 mechanism and/or shory patch excision repair are the most important for it. The interactions between the different DNA repair mechanisms are secondary. There is a strong correlation between ozone resistance and the capacity to reactivate T3 phages damaged by ozone.

• The Korean Journal of Food And Nutrition
• /
• v.11 no.4
• /
• pp.416-419
• /
• 1998

Identification of escherchia coli K1 polysaccharide antigen isolated from urine specimens of urinary tract infections in children were performed from of 1992 to 1993 in Kyoto, Japan. The serotypes of E. coli were categorized that O1:H7, O2:H6, O2:H7, O16:H6, O18:H7, O18:H￣, and O135:H44 among 14 strains isolated from urine specimens of urinary tract infections in children by the serological test. And, one strain (O18:H￣, isolation rate: 7.1%) of E. coli K1 polysaccharide antigen among 14 strains were isolated from urine specimens of urinary tract infections in children by the bacteriophage test.

• Korean Journal of Microbiology
• /
• v.29 no.2
• /
• pp.80-84
• /
• 1991

We cloned and expressed hepatitis B viral core antigen (HBcAg) gene in E. coli using $P_{L}$ promoter system. For optimal expression of the gene, we undertook the studies on the effects of the distance between Shine-Dalgarno (SD) sequence and start codon, copy number of repressor gene, induction temperature, and the stability of the core antigen. The results demonstrated that the induction at 37.deg.C was more efficient than at 42.deg.C, and the 11 base pairs (bp) distance between SD sequence and start codon of HBcAg gene was more efficient than the 15 bp distance in E. coli. The copy number of cI857 repressor gene did not influence on the expression of HBcAg, and the expression level of HBcAg in mutant type (low protease activity) and wild type strains was almost the same. The produced core antigen appeared to be HBcAg not HBeAg judged by two different radioimmunoassat (RIA) kits. This result suggested that the antigen was stable in E. coli.i.

• BMB Reports
• /
• v.30 no.1
• /
• pp.80-84
• /
• 1997

The synthesis and secretion of human angiogenin in E. coli by the natural leader sequence has been studied. We constructed a recombinant plasmid containing human angiogenin cDNA which encompassed all the coding region including leader sequence required for secretion. The recombinant plasmid was introduced into a suitable E. coli host. The angiogenin was detected in the culture medium and periplasm upon the induction of gene expression. The molecular weight of the secreted angiogenin was identical to that of authentic angiogenin purfied from human plasma when estimated by SDS-PAGE and immunoblotting. showing that the natural leader sequence was recognized and processed by the secretion machinery of E. coli. The angiogenin concentration in the culture medium reached a maximum within 2 h when expressed at $37^{\circ}C$ with 0.02~2 mM IPTG. In contrast, the expression level increased gradually over time up to 11 h at $23^{\circ}C$ with 0.002~2 mM IPTG and at $37^{\circ}C$ with 0.002 mM IPTG.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.6
• /
• pp.1346-1352
• /
• 2005

We have developed a modified gene replacement method using PCR products containing short homologous sequences of 40- to 50-nt. The method required $\lambda$-Red recombination functions provided under the control of a temperature-sensitive CI857 repressor expressed from the $P_{lac}$ promoter in the presence of IPTG on an easily curable helper plasmid. The method promoted the targeted gene replacements in the Escherichia coli chromosome after shifting cultures of the recombinogenic host, which carries the helper plasmid, to $42^{\circ}C$ for 15 min. Since this method employs $\lambda$-Red recombination functions expressed from the easily curable helper plasmid, multiple rounds of gene replacements in the E. coli chromosome would be possible. The procedures described herein are expected to be widely used for metabolic engineering of E. coli and other bacteria.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 1986.12a
• /
• pp.529.1-529
• /
• 1986

For isolation of the CMCase gene of the alkalophilic Bacillus sp. strain N-4 to analyze their genetic information for the multicomponents of the cellulase, Bscherichia coli K12 and plasmid DNA pBR322 was used as host-vector system. After the digestion of purified chromosomal DNA and plasmid DNA pBR322 with HindIII, these were ligated. The ligated DND were transformed into Escherichia coli, and recombinant plasmid 107 carried the gene coding for CMCase was constructed. The CMCase produced by Escherichia coli cells containing plasmid DNA pYBC107 was found in the cells as intracellular enzyme and nearly 60% of the total CMCase activity was localized in cellular fraction. Also, the optimum pH for the reaction of CMCase produced by Escherichia coli was appeared at pH .8.0 and the enzyme was stable between pH 7.0 and pH 8.0.

• Proceedings of the Korean Society for Applied Microbiology Conference
• /
• 1986.12a
• /
• pp.521.3-522
• /
• 1986

A gene encoding alcohol dehydrogenase (ADH) in Zymomonas mobilis was cloned into E. coli JM 83 with plasmid pUC 9. The ADH produced by the E. coli transformant was purified bysonication, (NH$^4$)2SO4 fractionation, Affi-Gel blue and hydroxylapatite chromatography. The ADH produced by Z. mobilis was also purified by the same procedures. The two enzyme preparations were characterized and compared. It was found that the E. coli ADH was identical to one of two ADH isozymes of Z. mobilis. Analytical gel filtrations led to the conclusion that the molecule of E. coli ADH was composedv of four subunits having molecular weight of 40,000 (+1,000) dalton each The effect of metal ions on ADH activity and optimum pH were investigated.

• Journal of Microbiology and Biotechnology
• /
• v.7 no.4
• /
• pp.282-286
• /
• 1997

The floc strength of Escherichia coli was enhanced by adding water soluble polymer flocculants (BPA-5020 and BPA-5000) to the particulate flocculant (BPA-1000) as indicated by the increase in the shear index. The shear index of the E. coli flocs increased from 0.39 with the particulate flocculant alone to 0.94 with the particulate flocculant in conjunction with the water soluble polymer flocculant. In addition, the sedimentation rate of flocs was higher and the sedimented volume of flocs was smaller when the particulate flocculant was used with the water soluble polymer flocculant. When E. coli was flocculated first with the water soluble flocculant and the particulate flocculant was added later into the E. coli flocs formed, the sedimentation rate of the flocs was greater than that of any other combination. The shear index of the flocs was, however, independent of the sequence of the flocculant addition.

• Microbiology and Biotechnology Letters
• /
• v.23 no.6
• /
• pp.665-670
• /
• 1995

A marine bacterium which produces extracelluar agarase was isolated from sea water. Isolated strain was identified as Pseudomonas sp. by the morphological and biochemical properties (1). HindIII restriction fragment of 3.2 kb from Pseudomonas genomic DNA was cloned into pUC19 to obtain recombinant plasmid pJA1 which enables E. coli JM83 to produce agarase. Most of agarase produced in E. coli was secreted into the culture medium. The enzyme (pJA1) showed the highest agarase activity during the stationary phase (20 hrs) of E. coli. The optimum temperature and pH were 40$\circ$C and 7.8, respectively. Restriction gene map anlaysis revealed that it has different restriction pattern with three kind of agarase gene reported.