• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2006.05a
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• pp.246-249
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• 2006

• Korean Journal of Microbiology
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• v.29 no.3
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• pp.149-154
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• 1991

Escherichia coli/Corynebacterium glutamicum shuttle vectors, pECCG1 and pECCG2 were constructed by joining a 3.00 kb cryptic plasmid pCB 1 from C. glutamicum and a 3.94 kb plasmid pACYC 177 from E. coli. By trimming unessential parts and introducing mulitiple cloning site into the plasmid pECCG 1, a plasmid pECCG122(5.1kb) was constructed. All the shuttle vectors were stably maintained in C. glutamicum up to about 40 generations irrespective of kanamycin addition in the medium. Threonine operon (homoserine dehydrogenase/homoserine kinase) and dapA gene (dihydrodipicolinate synthetase) of C. glutamicum were cloned into the plasmid pECCG122, and the resultant plasmids were designated pTN31 and pDHDP19, respectively. They were used to study the effect of cloned foreign gene on the stability of the plasmid pECCG122. Plasmids pTN31 and pDHDP19 were segregated rapidly from C. glutamicum when cultured in the medium without kanamycin. In medium with $50\mu${\g/ml} of kanamycin, their segregation rates were much slower than those in medium without kanamycin, but the danamycin addition didn't guarantee the complete maintenance of the plasmids in C. glutamicum.

• Microbiology and Biotechnology Letters
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• v.50 no.1
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• pp.63-70
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• 2022

Two small cryptic plasmids, pHG1 and pHG2, were isolated from Levilactobacillus zymae (formerly Lactobacillus zymae) GU240 and characterized. pHG1 is 1,814 bp in size with a GC content of 37.4% and contains two open reading frames. orf1 can potentially encode a protein of 101 amino acids (aa) with 99% identity with the copy number control protein of Lacticaseibacillus paracasei. orf2 can potentially encode a protein of 230 aa with 99% identity with a replication protein from multiple species. Six inverted repeats (IR I-VI) and six direct repeats (DR I-VI) were found in pHG1. pHG2 is 2,864 bp in size, with a GC content of 39.6%. pHG2 has two orfs. orf1 might encode a protein with 99% identity with the TrsL transmembrane protein. orf2 might encode a protein with 99% identity with plasmid recombination proteins from lactic acid bacteria. Both pHG1 and pHG2 may be useful as frames for constructing lactic acid bacteria-Escherichia coli shuttle vectors.

• Journal of Microbiology
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• v.45 no.3
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• pp.193-198
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• 2007

A marine bacterium was isolated from Mai Po Nature Reserve of Hong Kong and identified as Vibrio cholerae MP-1. It contains a small plasmid designated as pVC of 3.8 kb. Four open reading frames (ORFs) are identified on the plasmid, but none of them shows homology to any known protein. Database search indicated that a 440 bp fragment is 96% identical to a fragment found in a small plasmid of another V. cholerae. Further experiments demonstrated that a 2.3 kb EcoRI fragment containing the complete ORF1, partial ORF4 and their intergenic region could self-replicate. Additional analyses revealed that sequence upstream of ORF1 showed the features characteristic of theta type replicons. Protein encoded by ORF1 has two characteristic motifs existed in most replication initiator proteins (Rep): the leucine zipper (LZ) motif located at the N-terminal region and the alpha helix-turn-alpha helix motif (HTH) located at the C-terminal end. The results suggest that pVC replicates via the theta type mechanism and is likely a novel type of theta replicon.

• Korean Journal of Microbiology
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• v.50 no.3
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• pp.210-215
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• 2014

Pseudomonas nitroreducens TX1 was isolated from a rice field drainage in Taiwan. The bacterium is of special interest because of its capability to use a group of nonionic surfactants such as alkylphenol polyethoxylates even at high concentrations as a sole carbon source. In this study, a small cryptic circular plasmid, pTX1, was characterized from P. nitroreducens TX1. It is 2,286 bp in length with a GC content of 63.3% and harbors three open reading frames, $Rep_{pTX1}$ and functionally unidentified ORF1 and ORF2. The predicted $rep_{pTX1}$ gene product is homologous to Rep proteins of plasmids belonging to the pC194/pUB110 family, which is predominantly found in Gram-positive bacteria and is known to replicate by the rolling-circle mechanism. The copy number of pTX1 was estimated to be about 150 in each cell. Based on the genetic fingerprints and comparison with other plasmids, it is concluded that pTX1 replicates by a rolling circle mechanism which is rarely found for Pseudomonas plasmids.

• Proceedings of the Korean Society of Life Science Conference
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• 2005.04a
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• pp.153-153
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• 2005

• Proceedings of the Korean Society of Life Science Conference
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• 2000.09a
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• pp.78-78
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• 2000

• Food Science and Biotechnology
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• v.17 no.2
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• pp.438-441
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• 2008

A novel lactobacilli replicon from plasmids of Lactobacillus reuteri KCTC 3678 was isolated. Eight L. reuteri strains from Korean Collection for Type Cultures (KCTC) and Korea Food Research Institute (KFRI) were screened for cryptic plasmids and most strains harbored 1 or 2 plasm ids. Particularly, L. reuteri KCTC 3678 contained 6 plasm ids which all were used for screening of lactobacilli replicon. EcoRI digests of the plasmid DNA prep from L. reuteri KCTC 3678 were ligated with pUC19 and the recombinant DNAs were serially named from pLR1 to pLR7. A cat (chloramphenicol acetyltransferase; $Cm^r$) gene originated from pC194 was introduced into pLR1-7, resulting in pLR1cat-pLR7cat, respectively. The recombinant plasmids were introduced into L. reuteri KCTC 3679, and only transformants harboring pLR5cat were obtained, indicating that the insert in pLR5 functioned as a lactobacilli replicon.

• Microbiology and Biotechnology Letters
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• v.52 no.1
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• pp.88-90
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• 2024

We report the whole genome sequence of a linezolid-resistant and vancomycin-susceptible Enterococcus faecalis strain, ES-2-1, which was isolated from a pig stool in South Korea. The assembled genome of ES-2-1 consists of a 2,648,168-bp circular chromosome containing the optrA gene (encoding the ABC-F type ribosomal protection protein), an 84,891-bp plasmid containing numerous antimicrobial resistance genes, and an 82,106-bp cryptic plasmid. The ES-2-1 strain belongs to sequence type 1024 (ST1024) and carries multidrug resistant genes including the optrA (oxazolidinone phenicol transferable resistance A) gene, which confers linezolid resistance.

• Journal of Life Science
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• v.11 no.6
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• pp.530-536
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• 2001

Several bacterial strains utilizing crude oil as their sole carbon and energy source were isolated from marine environment polluted by crude oil. Among them, the selected strain 4A3 showed strong degradation activity for crude oil. This strain was identified as a Provindencia rettgeri 4A3 based on the morphological, biochemical, and physiological characteristics. The optimum cultural conditions was as follows; 26$^{\circ}C$ for temperature and 7.0 for initial pH. Additionally, the optimal concentration of sodium chloride was 2.0%, indicating that this strain was derived from sea water. The emulsifying activity of 4A3 was the highest after 3 days of cultivation under the condition of 2.0% sodium chloride, pH 7.0 and 26$^{\circ}C$. This strain had one cryptic plasmid in 7.0kb size.