• Journal of Microbiology and Biotechnology
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• v.22 no.9
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• pp.1279-1287
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• 2012

We established an efficient transformation method for thermophile Geobacillus kaustophilus HTA426 using conjugative transfer from Escherichia coli of host-mimicking plasmids that imitate DNA methylation of strain HTA426 to circumvent its DNA restriction barriers. Two conjugative plasmids, pSTE33T and pUCG18T, capable of shuttling between E. coli and Geobacillus spp., were constructed. The plasmids were first introduced into E. coli BR408, which expressed one inherent DNA methylase gene (dam) and two heterologous methylase genes from strain HTA426 (GK1380-GK1381 and GK0343-GK0344). The plasmids were then directly transferred from E. coli cells to strain HTA426 by conjugative transfer using pUB307 or pRK2013 as a helper plasmid. pUCG18T was introduced very efficiently (transfer efficiency, $10^{-5}-10^{-3}\;recipient^{-1}$). pSTE33T showed lower efficiency ($10^{-7}-10^{-6}\;recipient^{-1}$) but had a high copy number and high segregational stability. Methylase genes in the donor substantially affected the transfer efficiency, demonstrating that the host-mimicking strategy contributes to efficient transformation. The transformation method, along with the two distinguishing plasmids, increases the potential of G. kaustophilus HTA426 as a thermophilic host to be used in various applications and as a model for biological studies of this genus. Our results also demonstrate that conjugative transfer is a promising approach for introducing exogenous DNA into thermophiles.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.162-167
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• 2007

A genetic transfer system for introducing foreign genes to biomining microorganisms is urgently needed. Thus, a conjugative gene transfer system was investigated for a moderately thermophilic, extremely acidophilic biomining bacterium, Acidithiobacillus caldus MTH-04. The broad-hostrange IncP plasmids RP4 and R68.45 were transferred directly into A. caldus MTH-04 from Escherichia coli by conjugation at relatively high frequencies. Additionally the broad-hostrange IncQ plasmids pJRD215, pVLT33, and pVLT35 were also transferred into A. caldus MTH-04 with the help of plasmid RP4 or strains with plasmid RP4 integrated into their chromosome, such as E. coli SM10. The $Km^r\;and\;Sm^r$ selectable markers from these plasmids were successfully expressed in A. caldus MTH-04. Futhermore, the IncP and IncQ plasmids were transferred back into E. coli cells from A. caldus MTH-04, thereby confirming the initial transfer of these plasmids from E. coli to A. caldus MTH-04. All the IncP and IncQ plasmids studied were stable in A. caldus MTH-04. Consequently, this development of a conjugational system for A. caldus MTH-04 will greatly facilitate its genetic study.

• Korean Journal of Veterinary Research
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• v.28 no.2
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• pp.331-337
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• 1988

This paper dealt with the distribution of Salmonella (S) infection on 4 herds in Kyungju and Taegu during the period from May to October 1986. Isolated Salmonella were examined for serotypes, antimicrobial drug resistance and detection of R plasmid. The results obtained were summarised as followings: 1. Of total 4.622 samples from 4 herds, 67 Salmonella were isolated from 51 samples(1.1%), and their serovar strains were S typhimurium 6, S derby 5, S infantis 4, S bareilly 4, S dublin 3, S anatum 2, S montevideo 2 and untypable 41. 2. The isolation rate of Salmonella was higher in summer and autumn. 3. Of the 67 strains examined, 45 (67.2%) were resistant to one or more antibiotics, such as ampicillin (Am), cephalothin (Ce), chloramphenicol (Cm), rifampicin (Rf), sulfadimethoxine (Su), and tetracycline (Tc), and higher resistant to Sm (40.2%), Ce (31.3%), Am (23.9%). 4. Of the 45 resistant Salmonella strains, 44 (97.8%) harbored conjugative R plasmids and the transfer frequency of Sm (100%), Ce (95.2%), Tc (91.0%) and Su (80.0%) resistance was much higher than that of the other drug resistance. 5. The most common resistant patterns were Sm, Ce, AmCeCmSmSuTc, and AmCe. 6. In 4 herds, the incidience of drug resistance was 57.7%~100% and transfer frequency of conjugative R plasmid was 96.1%~100%.

• The Journal of the Korean Society for Microbiology
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• v.22 no.1
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• pp.95-99
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• 1987

When tetracycline resistancy were cured by ethidium bromide treatment, some of the cured strains lost the tetracycline resistance plasmid while other strains kept the plasmids. Both strains of lost and remained plasmids were digested with restriction endonuclease Hind III and these cleaved plasmids were compared with that of parent strains, two plasmid remained strains showed same cleavage patterns between parent and cured strains, however, one plasmid lost strain showed dissimilarity with parent strain, but in the other one strain, among 4 plasmid lost colonies, 2 showed same but other 2 showed different patterns compared to parent strain. Tetracycline was transfered by conjugation in on set(Staphylococcus aureus donor versus Staphylococcus epidermidis, recipient) with relative high frequency but the other 2 sets showed a low degree of frequency and the other 2 sets exhibited no transfer.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.269-278
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• 2023

Antibiotics either kill or inhibit the growth of bacteria. However, antibiotic-resistant bacteria are difficult to treat with antibiotics. Infections caused by such bacteria often lead to severe diseases. Antibiotic resistance genes (ARG) can be horizontally transmitted across different bacterial species, necessitating a comprehensive understanding of how ARGs spread across various environments. In this study, we analyzed the plasmid sequences of 33 extended-spectrum beta-lactamases (ESBL) producing Escherichia coli isolated from pigs, farms, and their owners. We conducted an antibiotic susceptibility test (AST) with aztreonam and seven other antibiotics, as well as whole genome sequencing (WGS) of the strains using MinION. Our results demonstrated that the plasmids that did not harbor ARGs were mostly non-conjugative, whereas the plasmids that harbored ARGs were conjugative. The arrangement of these ARGs exhibited a pattern of organization featuring a series of ARG cassettes, some of which were identical across the isolates collected from different sources. Therefore, this study suggests that the sets of ARG cassettes on plasmids were mostly shared between pigs and their owners. Hence, enhanced surveillance of ARG should be implemented in farm environments to proactively mitigate the risk of antibiotic-resistant bacterial infections.

• Macromolecular Research
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• v.12 no.5
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• pp.484-489
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• 2004

We have prepared a phenothiazine-based nonlinear optical (NLO) chromophore that displays a fairly high microscopic nonlinearity through intramolecular charge transfer. The phenothiazine unit plays important roles of contributing its high electron donating ability and connecting the resonance pathway through a conjugative effect in the cyclized ring adjacent to the aromatic ring. Theoretical calculations and an absorption spectroscopic study provided useful information concerning the microscopic nonlinearity of the chromophores. We investigated the electro-optic (EO) properties of the guest-host systems in amorphous polycarbonate containing the synthesized chromophores at different concentrations under different poling temperatures. A real-time pole and probe method provided a much greater amount of information regarding how the EO properties can arise and how they can be optimized.

• Korean Journal of Microbiology
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• v.52 no.1
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• pp.110-115
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• 2016

A small plasmid (pDK4) from the Antarctic marine organism Pseudoalteromonas sp. PAMC 21150, was purified, sequenced and analyzed. pDK4 was determined to be 3,480 bp in length with a G+C content of 41.64% and contains three open reading frames encoding a replication initiation protein (RepA), a conjugative mobilization protein (Mob) and a hypothetical protein. PCR-amplified pDK4 was cloned in high-copy pUC19 to yield the fusion vector pDOC153. The chloramphenicol resistance gene was inserted into pDOC153 to give an ampicillin and chloramphenicol-resistant, Pseudoalteromonas - Escherichia coli shuttle vector (7,216 bp; pDOC155). The TonB-dependent receptor (chi22718_IV ) and exochitinase (chi22718_III ) genes from Arctic marine P. issachenkonii PAMC 22718 were cloned into pDOC155 to produce pDOC158 and pDOC165, respectively. Both vector derivatives were transferred into plasmid-free Pseudoalteromonas sp. PAMC 22137 by the triparental mating method. PCR experiments showed that the genes were stably maintained both in Pseudoalteromonas sp. PAMC 22137 and E. coli $DH5{\alpha}$ cells, indicating the potential use of pDOC155 as a new gene transfer system into marine Pseudoalteromonas spp.

• Journal of Microbiology and Biotechnology
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• v.27 no.9
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• pp.1711-1715
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• 2017

In this study, we characterized the $bla_{NDM-5}$-bearing plasmid in a Klebsiella pneumoniae isolate that had lost the plasmid during serial passage. We determined the complete sequences of the plasmid pCC1410-2, which was extracted from a K. pneumoniae ST709 isolate collected at a Korean hospital from which two NDM-5-producing K. pneumoniae isolates were subsequently isolated. As a result, the pCC1410-2 plasmid had a backbone structure that was similar to those of two plasmids previously reported from the same hospital, but lacked some antibiotic resistance genes ($bla_{TEM-1}$, rmtB, mphR(A), mrx(A), and mph(A)). A 9-bp repeating unit encoding three amino acids (Gln-Gln-Pro) was inserted in TraD in pCC1410-2. Thus, the pCC1410-2 plasmid might be transferred from the previously identified carbapenem-resistant K. pneumoniae, but some delections and inversions might have occurred during the process. We compared the transfer frequency and stability of the plasmids. The relative frequency of conjugative transfer and stability in the host were significantly lower in pCC1410-2 than in previously reported $bla_{NDM-5}$-bearing plasmids in Korea. A low transfer frequency and instability in the host may cause underestimation of carbapenemase-producing Enterobacteriaceae in the clinical setting and in surveillance studies.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.77-84
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• 2005

We prepared the new nonlinear optical chromophores that show fairly high microscopic nonlinearity through intramolecular charge transfer. Phenothiazine and carbazole units played an important role to contribute high electron donability and connect the resonance pathway via conjugative effect in the cyclized ring beside the aromatic ring. Theoretical calculation, electrochemical analysis, and absorption spectroscopic study gave us useful information about the energy states and microscopic nonlinearities of two serial chromophores. We compared the microscopic nonlinearities of four chromophores with the conjugation length and electron donability in the push-pull type NLO chromophores. The effect of gradient donability and lengthening the conjugation were investigated on the electronic state and microscopic nonlinearity.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.974-981
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• 2020

Sequence type 410 (ST410) of Escherichia coli is an extraintestinal pathogen associated with multi drug resistance. In this study, we aimed to investigate the horizontal propagation pathway of a high-risk clone of E. coli ST410 that produces Klebsiella pneumoniae carbapenemase (KPC). blaKPC-encoding E. coli and K. pneumoniae isolates were evaluated, and complete sequencing and comparative analysis of blaKPC-encoding plasmids from E. coli and K. pneumoniae, antimicrobial susceptibility tests, polymerase chain reaction, multilocus sequence typing, and conjugal transfer of plasmids were performed. Whole-genome sequencing was performed for plasmids mediating KPC-2 production in E. coli and K. pneumoniae clinical isolates. Strains E. coli CPEc171209 and K. pneumoniae CPKp171210 were identified as ST410 and ST307, respectively. CPEc171209 harbored five plasmids belonging to serotype O8:H21, which is in the antimicrobial-resistant clade C4/H24. The CPKp171210 isolate harbored three plasmids. Both strains harbored various additional antimicrobial resistance genes. The IncX3 plasmid pECBHS_9_5 harbored blaKPC-2 within a truncated Tn4401a transposon, which also contains blaSHV-182 with duplicated conjugative elements. This plasmid displayed 100% identity with the IncX3 plasmid pKPBHS_10_3 from the K. pneumoniae CPKp171210 ST307 strain. The genes responsible for the conjugal transfer of the IncX3 plasmid included tra/trb clusters and pil genes coding the type IV pilus. ST410 can be transmitted between patients, posing an elevated risk in clinical settings. The emergence of a KPC-producing E. coli strain (ST410) is concerning because the blaKPC-2-bearing plasmids may carry treatment resistance across species barriers. Transgenic translocation occurs among carbapenem-resistant bacteria, which may spread rapidly via horizontal migration.