• 미생물학회지
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• 제43권3호
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• pp.166-172
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• 2007

ERM 단백질은 23S rRNA의 A2058에 methylation시킴으로써 macrolide-lincosamide- streptogramin B $(MLS_B)$계 항생제의 부착을 저해하여 항생제의 활성을 억제하는 내성 인자 단백질로 monomethylase와 dimethylase로 나누어진다. Dimethylase와 비교되는 monomethylase의 특성을 밝히기 위해 dimethylase (ErmSF)와 monomethylase (TlrD)를 동시에 보유한 Streptomyces fradiae에서 tlrD를 클론하고 대장균에서 최초로 대략생산을 시도하여 $37^{\circ}C$에서 세포내 전체 단백질의 55%를 차지할 정도로 대량생산된 불용성 단백질을 얻어내었다. 그러나 ErmSF와는 달리 낮은 온도에서 대량생산된 단백질이 용해성 단백질로 전환되지 않고 불용성 단백질로 남아있었다. Thioredoxin과 샤페론인 GroESL은 모두 ErmSF의 경우와 마찬가지로 용해성 단백질로의 전환에 도움을 주지 않았다. 이러한 차이점은 천재까지 전혀 밝혀지지 않은 단백질내의 구조적 특성에 의한 monomethylase와 dimethylase의 차이점을 밝힐 수 있다는 가능성을 말해주는 것으로 추정된다. 그러나 ErmSF의 경우와 동일하게 SDS-PAGE에서 검색되지 않은 미량의 발현된 용해성 단백질이 TlrD를 함유한 세포에 항생제에 대한 내성을 나타내게 하였고 이렇게 발현된 내성은 monomethylase에 의한 내성에서 기대되는 내성과 일치하였다.

• Journal of Microbiology
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• 제45권5호
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• pp.379-387
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• 2007

A hundred and seventeen antibiotic-resistant Escherichia coli strains were isolated from public tap and spring waters which were polluted by fecal coliforms. There were no significant differences between two water sources as to the coliform pollution level (p> 0.05). All E. coli isolates were detected to be resistant to one or more antibiotics tested. Nearly 42% of the isolates showed multiresistant phenotype. Three (2.5%) of these isolates contained class 1 integron. Sequencing analysis of variable regions of the class 1 integrons showed two gene cassette arrays, dfr1-aadA1 and dhfrA17-aadA5. Resistance to ampicillin, tetracycline or trimethoprim-sulfamethoxazole was transferable according to the results of conjugation experiments. The rate of tetracycline resistance was 15%. tet(A)-mediated tetracycline resistance was widespread among tetracycline-resistant E. coli isolates. Genotyping by BOX-polymerase chain reaction (BOX-PCR) showed that some of the strains were epidemiologically related. This is the first report on the prevalence and characterization of class 1 integron-containing E. coli isolates of environmental origin in Turkey.

• 한국미생물·생명공학회지
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• 제43권1호
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• pp.84-90
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• 2015

젓갈로부터 분리된 ampicillin 감수성, coagulase 음성 Staphylococcus 속 17 균주의 항생물질내성 및 위해성을 평가하였다. 15 균주는 한 종류 이상의 항생물질에 대한 내성을 나타내었고, penicillin G 내성 균주가 가장 높은 빈도로 검출되었다. PCR 증폭에 의한 항생물질내성 유전자 존재 확인 결과, trimethoprim 내성 관련 dfrA 유전자와 tetracycline 내성 관련 tetK 유전자를 각각 보유한 두 균주가 확인되었다. α 형 용혈활성은 검출되지 않았지만, 다섯 균주가 δ 형의 용혈을 나타내었고, 그 중 두 균주는 β 형 용혈활성을 나타냈으며, 12 균주가 biofilm을 형성하였다. 본 실험에서 수행한 모든 안전성 평가 결과는 균주 특이적으로 나타났다.

• Archives of Pharmacal Research
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• 제27권2호
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• pp.246-253
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• 2004

The prevalence, genotype for antibiotic resistance and antibiotic susceptibility of vancomycin resistant enterococci (VRE) were determined. And molecular typings of the Enterococcus faecium isolates were analyzed. Prevalence of VRE in chickens, healthy children and intensive care unit (ICU) patients was 41.6％,7.9％, and 20.4％, respectively. Forty out of 54 isolates from chicken intestines, and 9 out of 11 from ICU patients were identified as Enterococcus faecium. Eleven out of 13 isolates from non-hospitalized young children were E. gallinarium. Twelve strains of E. faecalis were isolated from chicken intestines. The gene for the antibiotic resistance in E. faecium, and E. faecalis was vanA, while that in E. gallinarium was vanC1. E. faecium isolates were resistant to most of antibiotics except ampicillin and gentamicin. Molecular typing of the E. faecium strains obtained by pulse field gel electrophoresis and repetitive sequence-based PCR suggest that VRE transmit horizontally from poultry to humans, especially young children, via the food chains in Korea.

• 한국미생물·생명공학회지
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• 제46권4호
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• pp.334-345
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• 2018

Spore-forming Bacillus species are commercially available probiotic formulations for application in humans. They have health benefits and help prevent disease in hosts by combating entero-pathogens and ameliorating antibiotic-associated diarrhea. However, the molecular and cellular mechanisms of these benefits remain unclear. Here, we report the draft genome of a potential probiotic strain of Bacillus clausii B106. We mapped and compared the probiotic profile of B106 with other reference genomes. The draft genome analysis of B106 revealed the presence of ADI pathway genes, indicating its ability to tolerate acidic pH and bile salts. Genes encoding fibronectin binding proteins, enolase, as well as a gene cluster involved in the biosynthesis of exopolysaccharides underscored the potential of B106 to adhere to the intestinal epithelium and colonize the human gut. Genes encoding bacteriocins were also detected, indicating the antimicrobial ability of this isolate. The presence of genes encoding vitamins, including Riboflavin, Folate, and Biotin, also indicated the health-promoting ability of B106. Resistance of B106 to multiple antibiotics was evident from the presence of genes encoding resistance to chloramphenicol, ${\beta}$-lactams, Vancomycin, Tetracycline, fluoroquinolones, and aminoglycosides. The findings indicate the significance of B. clausii B106 administration during antibiotic treatment and its potential value as a probiotic strain to replenish the health-promoting and disease-preventing gut flora following antibiotic treatment.

• 한국미생물·생명공학회지
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• 제49권3호
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• pp.449-457
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• 2021

The aim of the present study was to survey the frequency of inducible and constitutive phenotypes and inducible cross-resistant genes by regulating the methylation of 23S rRNA (ermA, ermB, and ermC) and macrolide efflux-related msrA gene in Staphylococcus aureus and S. epidermidis strains. A total of 172 bacterial isolates (identified based on standard tests), were examined in this study. Antibiotic susceptibility was determined by the disk diffusion method, and all isolates were evaluated with respect to inducible and constitutive phenotypes. The presence of ermA, ermB, ermC, and msrA genes was investigated by a PCR assay. The constitutive resistance phenotypes showed a higher distribution among the isolates. R phenotype was detected more among S. epidermidis isolates (46.25%). ermB, ermC, and msrA genes were detected more in methicillin-resistant S. aureus (MRSA) and methicillin-resistant S. epidermidis (MRSE) isolates that had R and HD phenotypes (>77% strains). The ermA gene had the lowest frequency among MRSA, MRSE, MSSA, and MSSE strains (<14% isolates). Distribution of inducible resistance genes in MRSA and MRSE strains, and possibly other species, leads to increased constitutive resistance to erythromycin, clindamycin, and other similar antibiotics. Therefore, it can be challenging to treat infections caused by these resistant strains.

• 한국융합학회논문지
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• 제6권5호
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• pp.77-84
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• 2015

본 연구는 항균제에 내성을 보이는 대장균의 특성을 알아보기 위해 설사환자에서 분리된 대장균에 대한 항균제 감수성 및 병원성 인자의 상관성을 분자융합적 기술을 통해 조사하였다. 분리한 대장균의 항균제 내성은 60주에서 ESBL(extendede spectrum ${\beta}$-lactamase) positive균주가 8주이고, negative균주는 52주였다. ESBL 양성 8주 중 2주는 병원성 유전자가 검출되지 않았으며, stb(3주), flich7(1주), flich7-eae(2주)로 나타났다. ESBL 음성 52주 중 26주는 병원성 유전자가 검출되지 않았고, stx1(3주), stb(10주), flich7 및 eae(각 2주), stx1-flich7(2주), stx1-stb(4주), flich7-stb(2주), flich7-stb-eae(1주)이었다. 결론적으로 항균제 내성이 증가하는 시대에 분자 융합적 관점에서 독력 유전자의 분포와 항균제 내성과의 관계는 적게 나타났으나, 향후 다양한 독력 유전자의 분석을 통한 융합기술연구가 이루어진다면 보다 정확한 병원성 인자를 추정할 수 있을 것으로 사료된다.

• Journal of Microbiology and Biotechnology
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• 제23권9호
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• pp.1293-1303
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• 2013

Antibiotic resistance of soilborne Acinetobacter species has been poorly explored. In this study, norfloxacin resistance of a soil bacterium, Acinetobacter oleivorans DR1, was investigated. The frequencies of mutant appearance of all tested non-pathogenic Acinetobacter strains were lower than those of pathogenic strains under minimum inhibitory concentration (MIC). When the quinolone-resistance-determining region of the gyrA gene was examined, only one mutant (His78Asn) out of 10 resistant variants had a mutation. Whole transcriptome analysis using a RNA-Seq demonstrated that genes involved in SOS response and DNA repair were significantly up-regulated by norfloxacin. Determining the MICs of survival cells after norfloxacin treatment confirmed some of those cells were indeed persister cells. Ten colonies, randomly selected from among those that survived in the presence of norfloxacin, did not exhibit increased MIC. Thus, both the low mutation frequency of the target gene and SOS response under norfloxacin suggested that persister formation might contribute to the resistance of DR1 against norfloxacin. The persister frequency increased without a change in MIC when stationary phase cells, low growth rates conditions, and growth-deficient dnaJ mutant were used. Taken together, our comprehensive approach, which included mutational analysis of the target gene, persister formation assays, and RNA sequencing, indicated that DR1 survival when exposed to norfloxacin is related not only to target gene mutation but also to persister formation, possibly through up-regulation of the SOS response and DNA repair genes.

• Journal of Plant Biotechnology
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• 제1권2호
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• pp.85-90
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• 1999

In order to protect fungal diseases, leaf disc explants of Solanum tuberosum cultivar, Belchip, was infected with an Agrobacterium MP90 strain containing chimeric gene construct, consisting of antibiotic resistance and chitinase gene driven by the CaMV 35S promoter, for transformation. Regenerated multiple shoots were selected on a medium containing kanamycin and carbenicillin after exposure to Agrobacterium. The presence and integration of the npt II and chitinase gene were confirmed by polymerase chain reaction(PCR). Northern blot analysis indicated that the genes coding for the enzyme could be expressed in potato plants. The chitinase activity of transgenic potato plants was higher than the control potato.

• 대한소아치과학회지
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• 제38권2호
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• pp.170-178
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• 2011

항생제 사용에 따라 구강내 세균들이 가지게 되는 내성의 발현이 문제가 될 수 있다. 어린이 치면세균막에서 치주질환의 원인균들과 흔히 사용하고 있는 항생제들에 대한 내성유전자의 출현율을 알아보고자 중합효소연쇄반응을 이용하여 조사하였다. 1. 치주질환 원인균의 출현율은 F. nucleatum 95.4%, T. forsythia 55.2% 이었으며, P. gingivalis 40.2%, A. actinomycetemcomitans 5.7%, T. denticola는 3.4% 순이었다. 2. 항생제 내성유전자의 출현율 조사에서 cephalosporin 분해효소인 cfxA는 100%에서 발견되었으며 ${\beta}$-lactam 분해효소인 $bla_{TEM}$과 tetracycline 내성유전자인 tet(M)도 100%의 출현율을 보였다. tet(Q)는 88.5%, ${\beta}$-lactam 분해효소인 $bla_{SHV}$는 29.9%, macrolide계 내성 ermF유전자는 87.4%, vancomycin 내성 vanA는 48.5%의 출현율을 보였다. Aminoglycoside에 대한 복합 내성을 보이는 aacA-aphD와 meticillin 내성유전자 mecA는 9.2%로 가장 낮은 출현율을 보였다. 3. 치주질환 원인균과 항생제 내성유전자와의 관련성 조사에서 T. forsythia와 $bla_{SHV}$간에 그리고 P. gingivalis와 vanA간 에 유의한 상관성이 있었다. 항생제 내성유전자 tet(Q)와 ermF (0.514)간에 중등도의 상관성을 나타내었으며, mecA와 vanA (0.25)간에 유의한 상관성을 나타내었다. 건강한 어린이들의 치면세균막에 다양한 치주질환 원인균들과 항생제 내성유전자들이 존재하며, 상호 관련성을 가지고 존재함을 보여주었다.