• 미생물학회지
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• 제33권2호
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• pp.125-130
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• 1997

미생물에 의한 6가이온 크롬의 3가이온으로의 환원은 세균에게 크롬내성을 제공할 수 있는 것으로 알려져 있다. 본 연구에서는 이러한 가설을 확인하기 위하여 크롬오염 토양과 오염되지 않은 토양으로부터 형태적으로 다른 20종의 세균을 순수분리하고 각각의 균주에서 크롬내성과 크롬환원능을 상호 비교하였다. 전자의 공여체로 glucose를 사용했을 때 세포현탁액에 의한 크롬의 환원은 시간당 0.014-0.305mM Cr(VI)의 범위로 관찰되었으며, 액체배지에서 2mM의 크롬에 대한 내성은 크롬을 첨가하지 않은 배지에서 배양한 경우와 혼탁도를 비교한 결과 전혀 저해를 받지 않는 경우부터 93.4%의 성장저해를 받는 경우까지 다양하게 관찰되었다. 이러한 결과로부터 상관관계를 분석한 결과 크롬내성과 크롬환원은 전혀 상관이 없는 것으로 계산되었다. 한편 군집수준에서의 크롬내성비교는 크롬오염 토양과 오염되지 않은 토양에서 각각 19.1%와 0.4%로 나타나 크롬의 존재는 내성균주의 선택적 성장을 유도하는 것으로 밝혀졌다. 그러나 이때 획득된 크롬에 대한 내성은 크롬의 환원에 의해서 제공되는 것이 아님을 상관관계 분석으로부터 알 수 있었다.

• 생명과학회지
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• 제15권4호
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• pp.641-646
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• 2005

Salmonella typhimurium TML이 Int-407 숙주세포에 부착하는 정도는 S. typhimurium이 낮은 농도의 철이 함유된 배지에서 배양되었을 때보다 LB 액체배지 또는 높은 농도의 철이 함유된 배지에서 생육한 것에서 약 10배 정도의 높은 수준으로 관찰되었다. 고농도의 철이 포함된 배양조건이 살모넬라가 숙주세포에 부착시키는 정도를 향상시키는데 반해, 칼슘, 코발트, 구리, 인산, 마그네슘 그리고 망간과 같은 다른 양이온은 그렇지 않다. 이것은 아마도 철이 Salmonella가 부착에 필요한 요소들의 발현을 활성화하는 역할을 하는 것으로 추정된다. 철 농도에 따른 부착정도의 차이들은 type 1 fimbriae, mannose resistant hemagglutinin과 flagellum등을 생성하지 않는 다양한 S. typhimurium 돌연변이주들에서도 관찰되는 것으로 미루어보아 이들 구조체들과 상관이 없는 밝혀지지 않은 어떤 인자가 부착성 증가에 관여하는 것으로 사료된다. fur유전자가 불활성화된 S. typhimurium 돌연변이주의 부착성이 야생형 Salmonella와 유사한 방식으로 철에 의해 조절되었는데, 이는 철 농도에 따른 부착성의 변화에 관여하는 잠재적인자의 발현이 Fur 단백질과 독립적으로 이루어진다는 것을 나타낸다.

• Journal of Microbiology and Biotechnology
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• 제26권6호
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• pp.1148-1161
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• 2016

Lactobacilli are universally recognized as probiotics that are widely used in the adjuvant treatment of inflammatory diseases, such as vaginitis and enteritis. With the overuse of antibiotics in recent years, the lactobacilli in the human body are killed, which could disrupt the microecological balance in the human body and affect health adversely. In this work, cephalosporin-resistant Lactobacillus casei RL20 was obtained successfully from the feces of healthy volunteers, which possessed a stable genetic set. However, the shortage of lactic acid (72.0 g/l at 48 h) by fermentation did not meet the requirement for its use in medicine. To increase the production of lactic acid, the functional genes pfk and glk were introduced into the wild strain. A yield of 144.2 g/l lactic acid was obtained in the transgenic L. casei RL20-2 after fermentation for 48 h in 1 L of basic fermentation medium with an initial glucose concentration of 100 g/l and increasing antibacterial activity. These data suggested that L. casei RL20-2 that exhibited a high yield of lactic acid may be a potential probiotic to inhibit the spread of bacterial infectious diseases and may be used for vaginitis therapy.

• Journal of Korean Medical Science
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• 제33권48호
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• pp.295.1-295.7
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• 2018

Background: Vancomycin-resistant enterococci (VRE) infections have become a major healthcare-associated pathogen problem worldwide. Nosocomial VRE infections could be effectively controlled by screening patients at high risk of harboring VRE and thereby lowering the influx of VRE into healthcare centers. In this study, we evaluated factors associated with VRE colonization in patients transferred to emergency departments, to detect patients at risk for VRE carriage. Methods: This study was conducted in the emergency department of a medical college-affiliated hospital in Korea. Every patient transferred to the emergency department and admitted to the hospital from January to December 2016 was screened for VRE using rectal cultures. In this cross-sectional study, the dependent variable was VRE colonization and the independent variables were demographic and clinical factors of the patients and factors related to the transferring hospital. Patients were divided into two groups, VRE and non-VRE, and previously collected patient data were analyzed. Then we performed logistic regression analyses of characteristics that differed significantly between groups. Results: Out of 650 patients, 106 (16.3%) had positive VRE culture results. Significant variables in the logistic analysis were transfer from geriatric long-term care hospital (adjusted odds ration [aOR]: 8.017; 95% confidence interval [CI]: 1.378-46.651), hospital days (4-7 days; aOR: 7.246; 95% CI: 3.229-16.261), duration of antimicrobial exposure (1-3 days; aOR: 1.976; 95% CI: 1.137-3.436), and age (aOR: 1.025; 95% CI: 1.007-1.043). Conclusion: VRE colonization in patients transferred to the emergency department is associated primarily with factors related to the transferred hospitals rather than demographic and clinical characteristics.

• 한국잠사학회:학술대회논문집
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• 한국잠사학회 1997년도 Progress and Future Development of Sericultural Science and Technology 40th Anniversary Commemoration Symposium
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• pp.23-49
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• 1997

This is a progress report of rice biotechnology including development of gene transformation system, gene cloning and molecular mapping in rice. The scope of the research was focused on the connection between conventional breeding and biotech-researches. Plant transformation via Agrobacterium or particle bombardment was developed to introduce one or several genes to recommended rice cultivars. Two chimeric genes containing a maize ribosome inactivating protein gene (RIP) and a gerbicide resistant gene (bar) were introduced to Nipponbare, a Japonica cultivar, and transmitted to Korean cultivars. The homozygous progenies of herbicide resistant transgenic plant showed good fertility and agronomic characters. To explore the genetic resourses in rice, over 8,000 cDNA clones from immature rice seed have been isolated and sequenced. About 13% of clones were identified as enzymes related to metabolic pathway. Among them, twenty clones have high homology with genes encoding enzymes in the photorespiratory carbon cycle reaction. Up to now about 100 clones were fully sequenced and registered at EMBL and GenBank. For the mapping of quantitative tarits loci (QTL) and eternal recombinant inbred population with 164 F13 lines (MGRI) was developed from a cross between Milyang 23 and Gihobyeo, Korean rice cultivars. After construction of fully saturated RFLP and AFLP map, quantitative traits using MGRI population were analyzed and integrated into the molecular map. Eighty seven loci were determined with 27 QTL characters including yield and yield components on rice chromosomes. Map based cloning was also tried to isolate semi-dwarf (sd-1) gene in rice. A DNA probe, RG 109, the most tightly linked to sd-1 gene was used to screen from bacterial artifical chromosome (BAC) libraries and five over lapping clones presumably containing sd-1 gene were isolated. Rice genetic database including results of biotech reasearch and classical genetics is provided at Korea Rice Genome Server which is accessible with world wide web (www) browser. The server provides rice cDNA sequences and map informations linked with phenotypic images.

• Journal of Microbiology and Biotechnology
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• 제31권1호
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• pp.115-122
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• 2021

Phenol-soluble modulins (PSMs) are responsible for regulating biofilm formation, persister cell formation, pmtR expression, host cell lysis, and anti-bacterial effects. To determine the effect of psm deletion on methicillin-resistant Staphylococcus aureus, we investigated psm deletion mutants including Δpsmα, Δpsmβ, and Δpsmαβ. These mutants exhibited increased β-lactam antibiotic resistance to ampicillin and oxacillin that was shown to be caused by increased N-acetylmannosamine kinase (nanK) mRNA expression, which regulates persister cell formation, leading to changes in the pattern of phospholipid fatty acids resulting in increased anteiso-C15:0, and increased membrane hydrophobicity with the deletion of PSMs. When synthetic PSMs were applied to Δpsmα and Δpsmβ mutants, treatment of Δpsmα with PSMα1-4 and Δpsmβ with PSMβ1-2 restored the sensitivity to oxacillin and slightly reduced the biofilm formation. Addition of a single fragment showed that α1, α2, α3, and β2 had an inhibiting effect on biofilms in Δpsmα; however, β1 showed an enhancing effect on biofilms in Δpsmβ. This study demonstrates a possible reason for the increased antibiotic resistance in psm mutants and the effect of PSMs on biofilm formation.

• 한국물환경학회지
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• 제27권3호
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• pp.334-341
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• 2011

The free residual chlorine of tap water samples, collected from 266 faucets on the water pipe network in Daegu City, was between 0.1 and 0.79 mg/L. On microorganic tests, general bacteria and the coliform goup were not detected and thus the tap water was turned out to be fit to drink. In particular, samples of which free residual chlorine was 0.1 mg/L and over were cultured in R2A agar media at $25^{\circ}C$ for 7 days, and as a result heterotrophic bacteria were detected in 65.9% of samples; (1). The closer tap water got to the faucet from the stilling basin, the lower residual chlorine concentration became but the more the bacterial count became. And, more bacteria were detected in the R2A agar medium than in the PCA medium. (2). In the case of separated strains, most colonies were reddish or yellowish. 16S rRNA sequence was identified as Methylobacterium sp. and Williamsia sp., and yellow strain was identified as Sphingomonas sp., Sphingobium sp., Novosphingobium sp., Blastomonas sp., Rhodococcus sp. and Microbacterium sp. White strain was identified as Staphylococcus sp. (3). Sterilized tap water in polyethylene bottles was inoculated with separated strain and was left as it was for 2 months. As a result, bio-film was observed in tap water inoculated with Methylobacterium sp. and Sphingomonas sp. It was found that heterotrophic bacteria increased when free residual chlorine was removed from tap water in the water pipe network. Thus, there is a need to determine a base value for heterotrophic bacteria in order to check the cleanliness of tap water in the water pipe network.

• Journal of Veterinary Science
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• 제19권6호
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• pp.808-816
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• 2018

Bacterial biofilms have been demonstrated to be closely related to clinical infections and contribute to drug resistance. Berberine, which is the main component of Coptis chinensis, has been reported to have efficient antibacterial activity. This study aimed to investigate the potential effect of a combination of berberine with ciprofloxacin (CIP) to inhibit Salmonella biofilm formation and its effect on expressions of related genes (rpoE, luxS, and ompR). The fractional inhibitory concentration (FIC) index of the combination of berberine with CIP is 0.75 showing a synergistic antibacterial effect. The biofilm's adhesion rate and growth curve showed that the multi-resistant Salmonella strain had the potential to form a biofilm relative to that of strain CVCC528, and the antibiofilm effects were in a dose-dependent manner. Biofilm microstructures were rarely observed at $1/2{\times}MIC/FIC$ concentrations (MIC, minimal inhibition concentration), and the combination had a stronger antibiofilm effect than each of the antimicrobial agents used alone at $1/4{\times}FIC$ concentration. LuxS, rpoE, and ompR mRNA expressions were significantly repressed (p< 0.01) at $1/2{\times}MIC/FIC$ concentrations, and the berberine and CIP combination repressed mRNA expressions more strongly at the $1/4{\times}FIC$ concentration. The results indicate that the combination of berberine and CIP has a synergistic effect and is effective in inhibiting Salmonella biofilm formation via repression of luxS, rpoE, and ompR mRNA expressions.

• The Plant Pathology Journal
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• 제37권6호
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• pp.555-565
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• 2021

Bacteriophages infecting Acidovorax citrulli, the causal agent of bacterial fruit blotch, have been proven to be effective for the prevention and control of this disease. However, the occurrence of bacteriophage-resistant bacteria is one of hurdles in phage biocontrol and the understanding of phage resistance in this bacterium is an essential step. In this study, we aim to investigate possible phage resistance of A. citrulli and relationship between phage resistance and pathogenicity, and to isolate and characterize the genes involved in these phenomena. A phage-resistant and less-virulent mutant named as AC-17-G1 was isolated among 3,264 A. citrulli Tn5 mutants through serial spot assays and plaque assays followed by pathogenicity test using seed coating method. The mutant has the integrated Tn5 in the middle of a cupin protein gene. This mutant recovered its pathogenicity and phage sensitivity by complementation with corresponding wild-type gene. Site-directed mutation of this gene from wild-type by CRISPR/Cas9 system resulted in the loss of pathogenicity and acquisition of phage resistance. The growth of AC-17-G1 in King's B medium was much less than the wild-type, but the growth turned into normal in the medium supplemented with D-mannose 6-phosphate or D-fructose 6-phosphate indicating the cupin protein functions as a phosphomannos isomerase. Sodium dodecyl sulfa analysis of lipopolysaccharide (LPS) extracted from the mutant was smaller than that from wild-type. All these data suggest that the cupin protein is a phosphomannos isomerase involved in LPS synthesis, and LPS is an important determinant of pathogenicity and phage susceptibility of A. citrulli.

• 생약학회지
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• 제53권2호
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• pp.87-95
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• 2022

Methicillin resistance Staphylococcus aureus (MRSA) is a gram-positive bacterium, the most commonly isolated bacterial human pathogen. JiYu-san is one of the natural products used to treat diseases in the folk recipe. In this study, we investigated the antimicrobial activity of EtOH 70% extracts of JiYu-san (JYS) against MRSA. The antibacterial activity of JYS against MRSA strain was evaluated using minimum inhibitory concentration (MIC), checkerboard dilution test, and time-kill assay. The effect of JYS on the immune mechanism of MRSA was confirmed through cell membrane permeability tests and energy metabolism tests, and the antibacterial activity mechanism was performed using qRT-PCR and western blot. As a result, in the antibacterial test of JYS, the MIC was measured to be 1.9~1000 ㎍/mL, and synergistic or showed a partial synergistic effect. In addition, JYS showed antibacterial activity in a combination test with DCCD or TX-100. In a study on the mechanism of action of antibacterial activity, it was found that JYS suppressed MRSA resistance genes and proteins. These results suggest that JYS has antibacterial activity and provides great potential as a natural antibiotic by modulating the immune mechanism against MRSA.