• The Journal of the Korean Society for Microbiology
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• v.17 no.1
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• pp.21-34
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• 1982

One hundred and twenty-one strains each of Escherichia coli isolated from stools of 60 patients who received various antimicrobial drugs in hospital for more than one week and apparently healthy 60 students who have no history of taking antimicrobial drugs during recent one month, were tested for their resistance to 13 antimicrobial drugs. The frequency of resistance strains was highest to tetracycline with 69.2%, and followed by streptomycin(Sm), sulfisomidine(Su), chloramphenicol(Cm), ampicillin(Ap), and carbenicillin(Cb) in the decreasing order, ranging from 61.2% to 39.3%. Strains resistant to kanamycin(Km), cephaloridine(Cr), and trimethoprim(Tp) occupied about one-fourth of strains, and only four strains were resistant either one or more of nalidixic acid, gentamicin and amikacin, and no strain was resistant to rifampicin. The frequency of resistant strains to Cm, Ap, Km, Cr, and Cb was much higher among patient isolates than student strains, but strains resistant to the other drugs showed almost the same frequencies between patient and student isolates. There was a marked difference in average minimum inhibitory concentrations of between resistant and susceptible strains, suggesting that the resistance to drugs is the plasmid origin. Seventy-six percent of strains were resistant to one to 10 drugs tested, and no much difference was observed between strains from patients and students. However, strains resistant to four or more drugs were much more frequently found among patient isolates than student strains, with the increasing tendency of multiply resistant strains among patient isolates following the increase in the number of resistant drugs. The transfer of drug resistance by conjugation was tested and 98 strains(67.5%) among 145 which were resistant to two or more drugs were found to transfer their drug resistance to E. coli. Among 74 strains resistant to 7 or more drugs, all except one transferred the resistance, and the number of strains with transferable resistance decreased, as the number of resistant drugs decrease. A R plasmid from randomly selected p13 strain was tested for the incompatibility group, and the plasmid was classified into Inc F II. R plasmM DNA bands were identified by polyacrylamide gel electrophoresis.

• Korean Journal of Microbiology
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• v.23 no.4
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• pp.282-290
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• 1985

Small size antibiotic resistance plasmids having molecular weights less than 10 Mdal were isolated and characterized from ten clinically isolated multiple resistant Staphylococcus aureus. Agarose gel electrophoresis profiles and antibiotic resistance patterns divided these strains into four groups. Strain 2-23-6, the representative strain of a group of five strains conferred two plasmids of molecular weights $1.6{\times}10^6\;dal\;and\;2.0{\times}10^6$ dal. The small plasmid (pSBK 112) specified macrolides, lincosamides and streptogramin type B (MLS) resistance gene which are expressed constitutively. Lage plasmid (pSBK 125) specified chloramphenicol resistance gene which is inducible. Strain 10-5 conferred a $3.0{\times}10^6$ dal plasmid (pSBK 141) which carry an inducible ampicillin resistance gene and strain P-H-2 conferred and $1.6{\times}10^6$ dal plasmid (pSBK 190) which carry a constitutive MLS resistance gene. Strain D-H-1 conferred four plasmids of molecular weights $0.8{\times}10^6$ dal (pSBK 201), $1.6{\times}10^6$ dal (pSBK 202), $2.5{\times}10^6$ dal (pSBK 203), and $1.2{\times}10^7$ dal (pDBK 204), respectively. Among those four plasmids, only pSBK 203 specified chloramphenicol resistance gene. Curing of constitutive MLS resistance using acriding orange or ethidium bromide in 2-23-6 and P-H-2 strains produced 'inducible' MLS resistance strains which are less resistant to MLS than the wild type strains, suggesting that there are two resistance genes in both strains; one is constitutive and the other is inducible.

• Korean Journal of Microbiology
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• v.27 no.4
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• pp.323-333
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• 1989

Plasmid DNA molecules containing strong promoter upstream from IS50L or IS50R, the two insertion sequences that flank Tn5, were constructed to amplify the synthesis of Tn5-encoded polypeptides. When proteins made by cells that contain these plasmids were analyzed on polyacrylamide gels, enhanced synthesis of IS50R polypeptides could be detected. Synthesis of this polypeptide apparently is initiated within the large open reading frame of this element. In addition, the stability of IS50L-and IS50R-encoded polypeptides was analyzed. It was found that IS50L polypeptides are relatively unstable in vivo. This instability could account for the observed inability of this element to promote transposition.

• Microbiology and Biotechnology Letters
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• v.32 no.3
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• pp.243-248
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• 2004

Production of (R)-3-hydroxybutyric acid (R3HB) by fed-batch culture and continuous culture of metabolically engineered Escherichia coli harboring Ralstonia eutropha PHB biosynthesis and depolymerase genes was examined in a 30 1 pilot-scale fermentor. A new stable two-plasmid system, pBRRed containing the R. eutropha PHB depolymerase gene and pMCS 105 containing the R. eutropha PHB biosynthesis genes, was developed. Among a variety of E. coli strains harboring plasmids, recombinant E. coli XL-10 Gold (pBRRed, pMCS105) was able to produce R3HB with the highest efficiency in a batch culture. By the fed-batch culture of recombinant E. coli XL-10 Gold(pBRRed, pMCS 105) in a 30 1 fer-mentor, the final R3HB concentration was 22.4 g/l giving a productivity of 0.97 g/l-h. To produce R3HB to a high concentration with high productivity, a new strategy of fed-batch culture followed by a continuous culture was investigated. The maximum productivity and R3HB concentration were 5.06 g/l-h and 25.3 g/l, respectively. These results show that economical production of R3HB is possible by recombinant E. coli in large scale.

• Journal of Yeungnam Medical Science
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• v.1 no.1
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• pp.41-48
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• 1984

The soil bacterium Agrobacterium tumefaciens is a plant pathogen that cause3 crown gall tumors by infecting the wounded dicotyledonous plants and subsequent integration of bacterial DNA into plant nuclear DNA. Virulent A. tumefaciens strains harbor a large Ti (tumor-inducing) plasmid that carries genes essential for tumorigenesis. In the present study, 13 strains (Malus pumila Mill; $A_{1-3}$, Populus monilifera; $W_{1-6}$, Populus tomentiglandlosa; $P_{1-3}$ and Rosa species; $R_1$) of Agrobacterium isolated in korean crown gall tumors and plasmids were observed in 6 strains ($W_2$, $W_3$, $W_6$, $P_1$, $P_3$ and $A_2$). The test for crown gall tumor formation was resulted only in ATCC15955 and $KW_2$ strains inoculated into the stem of sun flower and the development was observed for 4 and 6 weeks after inoculation. Above two Ti plasmids (pTi) were purified by cesium chloride-ethidium bromide density gradient centrifugation and digested with restriction enzyme and fragments of pTiATCC 15955 and $pTiKW_2$ observed by EcoR I ; 25&27, Hind III; 23&21, BamH I ; each 20 and Hpa I ; 12&27, and sizes of pTiATCC15955 and and $pTiKW_2$ calculated as 200 and 87 kbases. Octopine was isolated from tumor tissue ($W_{1-6}$ and $P_{1-3}$) and these strains confirmed as octopine type.

• Korean Journal of Microbiology
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• v.28 no.1
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• pp.27-34
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• 1990

Two macrolide-lincosamide-streptogramin B (MLS) antibiotic resistance genes, one expressed inducibly and the other expressed constitutively were recognized from a single Staphylococcus aureus DH1 strain. The inducible MLS resistance gene was isolated and cloned from the R-plasmid pDE1(7.4kb) and the constitutive gene was from chromosomal DNA. Base sequence of the inducible MLS resistance gene (1.2kb) was determined and found as same that of pE194. The restriction map of the cloned constitutive MLS resistance gene was compared with that of the inducible gene. Two genes have same restriction map except leader region. In the constitutive gene there is no leader region which is doing major role in inducible expression.

• The Journal of the Korean Society for Microbiology
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• v.19 no.1
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• pp.11-24
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• 1984

Shigella remains to be an important enteric pathogen in this country for the present. Moreover, most of the isolates have become multiple resistant to various antibiotics which used to be drugs of choice for shigellosis. This study was made as an attempt to assess the present stage of antibiotic resistance and the incidence and transferability of R factors of Shigella. A total of one hundred and seventeen strains of Shigella isolated from patients in Seoul and provincial area between 1982 and 1983 were tested for their resistant to antimicrobial agents and transmission of R-plasmid. Antibiotic susceptibilities were determined by an agar dilution method. Muller hinton agar were used for the assay of drug resistance and tryptic soy broth were used for propagating medium for conjugation. Shigella isolated found to be one or more antibiotics were considered potential donor of R-plasmid. The following results were obtained. 1. Among 117 strains of Shigella isolated, 111 strains(94.9%) were found to be resistant to one or more drugs tested and 97.3% of these resistant strains were multiply resistant, indicating the multiply resistant strains were more than the single resistant strains. Only six strains were susceptible to all drugs tested. 2. Among 117 strains of Shigella isolated, 107 strains(91.5%) were resistant to Tetracyclin(Tc), 106 strains(90.6%) to Chloramphenicol(Cp) and Streptomycin(Sm), 97 strains(82.9%) to Ampicillin(Ap), 68 strains(58.1%) to Cephaloridine(Cr), 10 strains(8.5%) to Nalidixic acid(Na), 5 strains(4.3%) to Kanamycin(Km) and 2 strains(1.7%) to Rifampicin. No strain was resisfant to Amikacin(Ak) and Gentamicin(Gm). 3. All drug-resistant Shigella strains, except three, were multiply resistant to two or more drugs. Fifty eight strains were resistant to five drugs, followed by 26 strains resistant to dour drugs, 12 strains resistant to three drugs and 11 strains resistant to six drugs. 4. The 73% of multiply drug-resistant Shigella transferred their resistance to E. coli by conjugation and the resistance was considered to be mediated by R-plasmid. Resistance to Nalidixic acid and Rifampicin were not transferred by conjugation to recipient. As for the transferability of resistance to each seperate drug, Ap resistance was transferred with 73.2% frequence and Cm and Tc resistance were transferred with approximately 50-60% frequence whereas Sm and Cr resistance were transferred in 19.1-21.4% The other four drugs resistant failed to transfer their resistance to recipient. 5. As for the incidence and transferability of resistance to each seperate drug, the strains resistant to Tc and Cm were encountered most frequently with the rate of 91-92%, whereas transfer of Tc and Cm were low, 51-52%. The incidence of Sm resistance was very high(90.6%) but transferability of drugs resistance was much lower(25.4%). Though the incidence of Km reristance was much lower(4.3%) transferability of Km resistance was considerably higher(60%). 6. The greater the multiplicity of resistance, the greater was the likelihood that part of all of the resistance markers would be transferable.

• Journal of Life Science
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• v.11 no.4
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• pp.385-391
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• 2001

Filamentous hemagglutinin (FHA) is considered as an essential immunogenic component for incorporation into acellular vaccines against Bordetella pertussis, the causative agent of whooping cough. Classically, antipertussis vaccination has employed an intramuscular route. An alternative approach to stimulate mucosal and systemic immune responses is oral immunization with recombinant live vaccine carrier strains of Salmonella typhimurium. An attenuated live Salmonella vaccine sgrain($\Delta$cya $\Delta$crp) expressing recombinant FHA(rFHA) was developed. Stable expressionof rFHA was achieved by the use of balanced-lethal vector-host system. which employs an asd deletion in the host chromosome to impose in obligate requirement for diaminopimelic acid. The chromosomal $\Delta$asd mutation was complemented by a plasmid vector possessing the asd$^{+}$ gene. A 3 kb DNA fragment encoding immuno dominant regionof FHA was subcloned in-frame downstream to the ATG translation initiation codon in the multicopy Asd$^{+}$ pYA3341 vector to create pYA3457. Salmonella vaccine harboring pYA3457 expressed approximately 105kDa rFHA protein. The 100% maintenance of [YA3457 in vaccine strain was confirmed by stability examinations. Additionally, a recombinant plasmid pYA3458 was constructed to overpress His(8X)-tagged rFHA in Essherichia coli. His-tagged rFHA was purified from the E. coli strain harboring pYA3458 using Ni$^{2+}$-NTA affinity purification system.>$^{2+}$-NTA affinity purification system.

• Microbiology and Biotechnology Letters
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• v.26 no.6
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• pp.566-568
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• 1998

Partial nucleotide sequence (nt 1-1842) of chloramphenicol resistance plasmid pKH7 has been reported previously and residual nucleotide sequence (nt 1843-4118) of pKH7 was determined and then the complete nucleotide sequence of pKH7 was obtained. pKH7 consists of 4118 bp and has three ORFs. Besides Rep and CAT proteins described in previous paper, Pre protein which mediates site-specific recombination in Staphylococcus aureus was found to be on pKH7. R $S_{A}$, a site-specific recombination site of Pre protein, and palA, a specific lagging-strand conversion signal, was also found in pKH7. Amino acid sequence of Pre protein of pKH7 was compared with those of other antibiotic resistant Staphylococcus aureus plasmids.s.

• Journal of Microbiology and Biotechnology
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• v.3 no.4
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• pp.261-265
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• 1993

A sopA protein (41K) encoded by plasmid pXX288 was observed in the cytoplasm, whereas a sopB protein (37K) encoded by plasmid pXX157 was observed in the membrane fraction. Most of the sopB protein was solubilized from the crude membrane by treatment with Sarkosyl, which suggested that the protein may be located in the inner membrane. The sopA protein was precipitated at the concentration of 30 to 60% ammonium sulfate. The sedimentation profile of the crude membrane fraction showed a little difference according to culture media used, and the sopB protein existed in all fractions of inner membrane. The DNA of plasmids, pXX157, pXX300, and pXX167 co-sedimented with inner membrane fraction.