• Journal of Microbiology and Biotechnology
• /
• v.19 no.11
• /
• pp.1408-1414
• /
• 2009

The obtention of high yields of purified plasmid DNA is viewed as an essential issue to be considered towards efficient production of DNA vaccines and therapeutic plasmids. In this work, Escherichia coli $DH5\alpha$. bearing the pVAXI-LacZ plasmid was grown in a developed semi-defined medium at different temperatures and tryptone concentrations. Analysis of pDNA yields and E. coli morphology revealed that at higher temperatures (37 and $40^{\circ}C$), higher specific yields and E. coli filamentation were obtained. However, the best results were achieved when a lower tryptone concentration was used. This approach was shown to be a powerful tool to promote plasmid amplification, keeping the desirable plasmid structure, and favoring the attainment of quality. Our results suggest that by using tryptone alone as an amino acid source, pDNA amplification was improved and a specific yield of 20.43 mg pDNA/g dcw was achieved, proving that this strategy can improve pDNA yield even at a small scale.

• Microbiology and Biotechnology Letters
• /
• v.18 no.4
• /
• pp.433-436
• /
• 1990

The TOL plasmid, pWWO, conjugally transferred from Pseudomonas putida mt-2 was dissociated into TOL* and TOL $\Delta$A in P. putidu PpGl carrying CAM plasmid. The TOL* was integrated into the CAM plasmid, and the resulting plasmid was designated as CAM::TOL*. The introduction of NAH plasmid, belonging to Inc P9 incompatibility group, into P. putida CSTBA carrying CAM::TOLt plasmid and TOL A plasmid did not affect m-toluate catabolism, but resulted in expelling the TOL $\Delta$ plasmid.

• BMB Reports
• /
• v.29 no.1
• /
• pp.63-67
• /
• 1996

In order to elucidate the molecular mechanism of plasmid incompatibility of broad host-range plasmid R1162, the plasmid-encoded replication protein RepIB was purified and tested for binding to the 20 bp direct repeat (DR) DNA sequence which is reiterated 3 and 1/2 times within the replicative origin of the plasmid. The RepIB protein specifically binds to the DR DNA. Point mutations in the DR which affect expression of plasmid incompatibility also coordinately affect binding. These results indicate that the incompatibility of broad host-range plasmid R1162 is exerted by the DR DNA by titrating the essential replication protein RepIB.

• Korean Journal of Veterinary Research
• /
• v.47 no.2
• /
• pp.157-162
• /
• 2007

Lactic acid bacteria (LAB) has been regarded as a useful microorganism and tried to manipulate plasmid DNA for increasing the usefulness. Although several methods have been developed to isolate plasmid DNA from Escherichia coli (E. coli), these methods were not sufficient to apply to LAB with exception of O'Sullivan's lysis method. So, we evaluated plasmid DNA extraction from LAB using general E. coli preparation methods and tried to improve the extraction yield and DNA purity by modifying O'Sullivan's alkaline lysis method. To improve the extraction yield, salt and carrier were added to precipitant and those were incubated at $-70{^{\circ}C}$. Only incubation at $-70{^{\circ}C}$ was the effective method of those modifications. Purity of plasmid DNA was improved by two times of each centrifugation and phenol/chloroform extraction. However, DNA was damaged by twice extraction with phenol/chloroform. Also, exclusion of ethidium bromide showed negative effect to purity. Additionally, it was recommended that improvement of the extraction yield may be due to centrifugation at high speed for more time and to dissolving complete DNA pellet before addition of 7.5 M ammonium acetate. Extraction using this modification produced higher quality of plasmid DNA.

• BMB Reports
• /
• v.37 no.3
• /
• pp.351-355
• /
• 2004

Separate protocols are commonly used to prepare plasmid DNA, chromosomal DNA, or total RNA from E. coli cells. Various methods for the rapid preparation of plasmid DNA have been developed previously, but the preparation of the chromosomal DNA and total RNA are usually laborious. We report here a simple, fast, reliable, and cost-effective method to extract total nucleic acids from E. coli by direct lysis of the cells with phenol. Five distinct and sharp bands, which correspond to chromosomal DNA, plasmid DNA, 23S rRNA, 16S rRNA, and a mixture of small RNA, were observed when analyzing the prepared total nucleic acids on a regular 1-2% agarose gel. The simple and high-quality preparation of the total nucleic acids in a singe tube allowed us to rapidly screen the recombinant plasmid, as well as to simultaneously monitor the change of the plasmid copy number and rRNA levels during the growth of E. coli in the liquid medium.

• Korean Journal of Microbiology
• /
• v.33 no.4
• /
• pp.274-276
• /
• 1997

Transformation of Coprinus congregatus with a linearized plasmid has been successfully carried out using phosphinothricin resistance gene as a dominant selectable marker. The transforming frequency was about 500 transformants per microgram of DNA using the protoplast-$CaCl_2$ method. The transforming vector pBARGEM 7-1 which had the phosphinothricin resistance gene was detected in the restriction enzyme fragments of chromosomal DNA from a transformant by Southern hybridization.

• Journal of Microbiology and Biotechnology
• /
• v.15 no.5
• /
• pp.1022-1027
• /
• 2005

Based on plasmid display technology by the complexes of fusion protein and the encoding plasmid DNA, an in vitro selection method for high affinity DNA-binding protein was developed and experimentally demonstrated. The GAL4 DNA-binding domain (GAL4 DBD) was selected as a model DNA-binding protein, and enhanced green fluorescent protein (EGFP) was used as an expression reporter for the selection of target proteins. Error prone PCR was conducted to construct a mutant library of the model. Based on the affinity decrease with increased salt concentration, mutants of GAL4 DBD having high affinity were selected from the mutant protein library of protein-encoding plasmid complex by this method. Two mutants of (Lys33Glu, Arg123Lys, Ile127Lys) and (Ser47Pro, Ser85Pro) having high affinity were obtained from the first generation mutants. This method can be used for rapid in vitro selection of high affinity DNA-binding proteins, and has high potential for the screening of high affinity DNA-binding proteins in a sequence-specific manner.

• Journal of Pharmaceutical Investigation
• /
• v.39 no.5
• /
• pp.339-343
• /
• 2009

Recently, co-delivery of drug and gene has been attempted for higher therapeutic effects of anticancer agents. In this study, cationic liposomes were prepared using 1,2-dioleoyl-3-trimethylammoniopropane (DOTAP) as a cationic lipid to investigate the effect of drug loading on the physicochemical characteristics of cationic liposomes/DNA complexes. The complex formation between cationic liposomes and negatively charged plasmid DNA was confirmed and the protection from DNase was observed. Particle size of complexes was reduced not by drug loading, but by the increased ratio of cationic lipid to plasmid DNA. Meanwhile, zeta potential of complex was increased by the addition of cationic liposomes to complexes and the effect of drug loading on the zeta potential was not much higher than on particle size. Gel retardation of complexes was indicated when the complexation weight ratios of cationic lipid to plasmid DNA were higher than 24:1 for drug free complexes and 20:1 for drug loaded ones, respectively. Agarose gel retardation showed the similar complexation between plasmid DNA and drug free liposomes or drug loaded liposomes. Both complexes protected plasmid DNA from DNase independent of complexation temperature. From the results, drug loading may affect not the complex formation of cationic liposomes and plasmid DNA, but the particle size of complex.

• Microbiology and Biotechnology Letters
• /
• v.13 no.4
• /
• pp.417-422
• /
• 1985

Streptococcus faecalis var. liquefaciens was examined for the presence of plasmid deoxyribonucleic acid. An analysis by agarose gel electrophoresis revealed the presence of at least four plasmids of approxymately 6.8, 5.2, 2.6, and 2.1 Mdal. Two plasmid cured strains were obtained by novobiocin treatment. SKR2, which lost 5.2 mdal plasmid (pSK2) and 2.1 Mdal plasmid(pSK4) was sensitive to lincomycin and erythromycin. However, all cured strains showed identical response as parental strain in sugar fermentation, temperature sensitivity, proteolytic activity, and liquefaction of gelatin. The results imply that pSK2 or pSK4 is associated with antibiotic resistance of Str. faecalis var. liquefaciens.

• Journal of Life Science
• /
• v.14 no.3
• /
• pp.406-410
• /
• 2004

Glyoxal or methylglyoxal was incubated with catalase in 0.24 M sodium phosphate buffer (pH 7.4) at 37$^{\circ}C$. Dicarbonyls modify and inactivate catalase. Plasmid DNA that is directly incubated with glycation propagators, glyoxal and methylglyoxal, showed different DNA mobility shift compared to nomal plasmid DNA. When plasmid DNA is added in Fenton reaction with glycated catalase, plasmid DNA was significantly strand broken and 8-hydroxydeoxyguanosine production was time dependently increased. These results suggest that glycation of antioxidant is synergistic effect to oxidative stress.