• 한국미생물·생명공학회지
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• 제14권3호
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• pp.245-250
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• 1986

청주시 무심천의 하천수에서 항생물질에 내성을 나타내는 Gram 음성 세균을 분리하여 수질환경에서 일어나는 R 플라스미드의 전이를 연구하였다. 분리된 균주사이에서 접합에 의한 R 플라스미드의 전이는 실험실 환경에서 1.1$\times$$10^{-6}$-1.2$\times$$10^{-7}$, 하천의 수질환경에서 1.2$\times$$10^{-7}$-1.0$\times$$10^{-9}$으로 나타나, 자연의 수질환경에서도 R 플라스미드의 전이가 일어남을 확인하였다. 또 T-44 균주의 Ap$^{r}$Cm$^{r}$Tc$^{r}$ 플라스미드는 형질전환에 의하여 E. coli HB 101에 1.7$\times$$10^{-6}$의 비율로 전이되었다. 분자의 크기가 약 9.01kb로 측정된 Ap$^{r}$Cm$^{r}$Tc$^{r}$플라스미드 DNA를 제한효소로 처리한 결과 이 플라스비드에는 EcoRI과 BamHI의 절단부위가 각각 하나씩 존재하고 P-stI의 절단부위는 3개가 있었다.

• 한국미생물·생명공학회지
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• 제23권2호
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• pp.164-169
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• 1995

An endogenous cryptic plasmid, pBL1, which has been used to construct plasmid vectors for coryneform bacteria producing amino acids, was eliminated from Brevibacterium lactofermentum. The pBL1 was partially digested with Sau3AI and the resulting DNA fragments were subcloned into a suicide vector pEM1 which contains a kanamycin-resistant (km$^{r}$) gene. KM$^{r}$ B. lactofermentum transconjugants were obtained by conjugal transfer of the pEM1 derivatives containing pBL1 DNA fragments from Escherichia coli into B. lactofermentum. A km$^{r}$ transconjugant was analyzed to contain a plasmid pEB14, which occurred in vivo by homologous recombination between pBL1 and the conjugal-transferred plasmid. The pEB14 including the pEM1-derived km$^{r}$ gene was found to be lost concomitantly with km$^{r}$ phenotype, resulting in the construction of a pBL1-free strain of B lactofermentum. Based on transformation efficiencies and plasmid stability, the resultant pBL1- free strain is more useful than wild strain as a host cell for genetic manipulation. It could be concluded that foreign plasmid DNAs are efficiently isolated and analyzed from the pBL1-free strain because of the absence of endogenous pBL1 plasmid.

• Journal of Microbiology and Biotechnology
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• 제2권3호
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• pp.174-182
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• 1992

The hemagglutinin-esterase glycoprotein (HE) gene of bovine coronavirus, coupled with a simian virus 40 early promoter and polyadenylation signal, was inserted into a human adenovirus transfer vector. The transfer vector was used to co-transfect 293 cells along with adenovirus genomic DNA. The hemagglutinin-esterase transcription unit was rescued into the adenovirus genome by homologous in vivo DNA recombination between the vector plasmid DNA and the adenovirus genomic DNA, and a recombinant adenovirus was isolated by several rounds of plaque assays. Thus the recombinant adenovirus carries the hemagglutinin-esterase gene in the early transcription region 3 (E3) of the adenovirus genome in the parallel orientation to the E3 transcription. The recombinant adenovirus synthesized the HE polypeptide in HeLa cells as demonstrated by immunoprecipitation with anti-coronavirus rabbit antisera. The recombinant HE polypeptide could be labelled by $[^3H]$glucosamine, demonstrating that the recombinant HE was glycosylated. Cells expressing the HE polypeptide exhibited hemadsorption activity when incubated with mouse erythrocytes. The HE was transported to the plasma membrane as shown by the cell surface immunofluorescence, indicating that the recombinant HE polypeptide retained its biological activities. Potential for the use of infectious recombinant adenovirus as a live virus-vectored vaccine candidate for bovine coronavirus disease is discussed.