• Journal of Microbiology and Biotechnology
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• 제12권1호
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• pp.114-120
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• 2002

A 1,989-bp genomic region encoding nickel resistance genes was isolated from Legionella pneumophila, a pathogen for legionellosis. From a sequencing and computer analysis, the region was found to harbor two structural genes, a nreB-like protein gene (1,149 bp) and a nreA-like protein gene (270 bp), in a row. Both genes exhibited a significant degree of similarity to the corresponding genes from Synechocystis sp. PCC6803 ($54\%$ amino acid sequence identity) and Achromobacter xylosoxidans 31A ($76\%$). The gene was successfully expressed in E. coli MG1655 and conferred a nickel resistance of up to 5 mM in an LB medium and 3 mM in a TMS medium including gluconate as the sole carbon source. E. coli harboring the nickel resistance gene also exhibited a substantial resistance to cobalt, yet no resistance to cadmium or zinc. Since the extracellular concentration of nickel remained constant during the whole period of cultivation, it was confirmed that the nickel resistance was provided by an efflux system like the $Ni^2＋$permease (nrsD) of Synechocystis sp. strain PCC6803. Since polyphosphate (poly-P) is known as a global regulator for gene expression as well as a potential virulence factor in E. coli, the nickel resistance of a ppk mutant of E. coli MG 1655 harboring the nickel resistance gene from L. pneumophila was compared with that of its parental strain. The nickel resistance was significantly attenuated by ppk inactivation, which was more pronounced in an LB medium than in a TMS medium.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2015년도 춘계학술대회 및 임시총회
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• pp.59-59
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• 2015

Cryptococcus neoformans causes life-threatening meningoencephalitis in humans, but the treatment of cryptococcosis remains challenging. To develop novel therapeutic targets and approaches, signaling cascades controlling pathogenicity of C. neoformans have been extensively studied but the underlying biological regulatory circuits remain elusive, particularly due to the presence of an evolutionarily divergent set of transcription factors (TFs) in this basidiomycetous fungus. In this study, we constructed a high-quality of 322 signature-tagged gene deletion strains for 155 putative TF genes, which were previously predicted using the DNA-binding domain TF database (http://www.transcriptionfactor.org/). We tested in vivo and in vitro phenotypic traits under 32 distinct growth conditions using 322 TF gene deletion strains. At least one phenotypic trait was exhibited by 145 out of 155 TF mutants (93%) and approximately 85% of the TFs (132/155) have been functionally characterized for the first time in this study. Through high-coverage phenome analysis, we discovered myriad novel TFs that play critical roles in growth, differentiation, virulence-factor (melanin, capsule, and urease) formation, stress responses, antifungal drug resistance, and virulence. Large-scale virulence and infectivity assays in insect (Galleria mellonella) and mouse host models identified 34 novel TFs that are critical for pathogenicity. The genotypic and phenotypic data for each TF are available in the C. neoformans TF phenome database (http://tf.cryptococcus.org). In conclusion, our phenome-based functional analysis of the C. neoformans TF mutant library provides key insights into transcriptional networks of basidiomycetous fungi and ubiquitous human fungal pathogens.

• 한국축산식품학회지
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• 제35권4호
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• pp.502-506
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• 2015

The aim of this study was to investigate the antimicrobial resistance profiles of and the enterotoxin gene distribution in 4 strains of Staphylococcus aureus (S10-2, S10-3, S12-2, and S13-2) isolated from 90 bulgogi samples. The S. aureus enterotoxin H gene (seh) was found in all the strains, while the S. aureus enterotoxin A gene (sea) was found only in 3 of the 4 strains. The S10-2 strain expressed a combination of enterotoxin genes - seg, seh, sei, sej, selm, and seln. The strains S10-2 and S13-2 were resistant to ampicillin and penicillin G, and all the isolated strains were resistant to tetracycline. The S10-2 strain was the only mecA-positive strain; it was also resistant to β-lactam antibiotics. Thus, genes encoding enterotoxin as well as those conferring antibiotic resistance were identified in the S. aureus strains isolated from pork bulgogi. These results represents the potential occurrence of MRSA in pork bulgogi, and the need for a monitoring system for pork bulgogi in order to prevent an outbreak of staphylococcal food poisoning.

• International Journal of Oral Biology
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• 제35권3호
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• pp.121-128
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• 2010

Porphyromonas gingivalis lipopolysaccharide (Pg LPS) is an important virulence factor in chronic periodontitis. The aim of this study was to compare the expression of inflammatory cytokine genes in Escherichia coli LPS (Ec LPS) and Pg LPS-stimulated mouse macrophage RAW 264.7 cells. Cells were treated with Ec LPS and Pg LPS for 18 hours, and the cytokine gene expression profile was assessed using microarrays and confirmed by real-time PCR. Microarray analysis showed that both types of LPS induced a significant increase in the expression of IL-$17{\beta}$, IL-2, Ccl4, Cxcl2 and $TNF{\alpha}$ compared with the control. However, LT-b was up-regulated by Pg LPS but not by Ec LPS. Real-time PCR analysis of these genes showed similar results for LT-b, Ccl4, Cxcl2, and TNF-$\alpha$ but found that IL-$17{\beta}$ and IL-2 were upregulated by Pg LPS but not by Ec LPS. These data indicate that Pg LPS stimulates the transcription of IL-$17{\beta}$, IL-2, Ccl4, Cxcl2, LT-b, and $TNF{\alpha}$, all of which may be involved in the pathogenesis of chronic periodontitis.

• Journal of Microbiology
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• 제44권4호
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• pp.409-416
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• 2006

Clarithromycin resistance in Helicobacter pylori is a principal cause of failure of eradication therapies, and its prevalence varies geographically. The IceA gene is a virulence factor associated with clinical outcomes. The objective of this study was to determine the current state of clarithromycin resistance prevalence, and to investigate the role of iceA genotypes in 87 Turkish adult patients (65 with functional dyspepsia and 22 with duodenal ulcer). A2143G and A2144G point mutations were tested by PCR-RFLP for clarithromycin resistance. Among the patients in the study, 28 patients were tested by agar dilution as well. Allelic variants of the iceA gene were identified by PCR. A total of 24 (27.6%) strains evidenced one of the mutations, either A2143G or A2144G. IceA1 was found to be positive in 28 of the strains (32.2 %), iceA2 was positive in 12 (13.8 %) and, both iceA1 and iceA2 were positive in 22 (25.3 %) strains. In conclusion, we discovered no relationships between iceA genotypes and functional dyspepsia or duodenal ulcer, nor between clarithromycin resistance and iceA genotypes. clarithromycin resistance appears to be more prevalent in Turkish patients.

• Genomics & Informatics
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• 제21권1호
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• pp.13.1-13.8
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• 2023

Importance of accurate molecular diagnosis and quantification of particular disease-related pathogenic microorganisms is highlighted as an introductory step to prevent and care for diseases. In this study, we designed a primer/probe set for quantitative real-time polymerase chain reaction (qRT-PCR) targeting rgpA gene, known as the specific virulence factor of periodontitis-related pathogenic bacteria 'Porphyromonas gingivalis', and evaluated its diagnostic efficiency by detecting and quantifying relative bacterial load of P. gingivalis within saliva samples collected from clinical subjects. As a result of qRT-PCR, we confirmed that relative bacterial load of P. gingivalis was detected and quantified within all samples of positive control and periodontitis groups. On the contrary, negative results were confirmed in both negative control and healthy groups. Additionally, as a result of comparison with next-generation sequencing (NGS)-based 16S metagenome profiling data, we confirmed relative bacterial load of P. gingivalis, which was not identified on bacterial classification table created through 16S microbiome analysis, in qRT-PCR results. It showed that an approach to quantifying specific microorganisms by applying qRT-PCR method could solve microbial misclassification issues at species level of an NGS-based 16S microbiome study. In this respect, we suggest that P. gingivalis-specific primer/probe set introduced in present study has efficient applicability in various oral healthcare industries, including periodontitis-related microbial molecular diagnosis field.

• 한국미생물·생명공학회지
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• 제46권3호
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• pp.261-268
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• 2018

Differences in host ethnicities and geographical distributions may influence the genetic variation and pathogenesis of Helicobacter pylori strains, particularly with respect to those with a high risk of gastric cancer and in Asian Enigma regions. We simultaneously identified H. pylori virulence-associated genes involved in inflammation and cell damage in Thai and Korean dyspeptic patients. The virulence-associated gene cagA, cagA genotypes (East Asian and Western type cagA), vacA genotypes (s- and m-), oipA, and sabA were detected in Thai and Korean dyspeptic patients by polymerase chain reaction (PCR), real-time PCR, and DNA sequence analysis. Comparisons between the two regions showed that cagA, East Asian type cagA, and vacA s1/m1 in Korean dyspeptic patients occurred at rates of 100%, 86.67%, and 88.89%, respectively (p < 0.05). The oipA- and sabA-positive samples were significantly more predominant in the Korean population (95.56%, 91.11%) than in the Thai population (32%, 34%). DNA sequence analysis revealed differences in the patterns of cytosine-thymine dinucleotide repeats of oipA and sabA among the two populations of dyspeptic patients. Our results indicate that the H. pylori strains detected in the two regions were divergent, and strains colonizing the Korean dyspeptic patients may be more virulent than those in the Thai population. Our data may help explain H. pylori pathogenesis in Asian Enigma areas with a low gastric cancer incidence. However, other factors involving H. pylori infection in these two regions should be further analyzed.

• 미생물학회지
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• 제35권3호
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• pp.248-252
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• 1999

한국의 환경에서 분리된 47주와 환자 혈액에서 분리된 18주의 Vibrio cholerae serovar non-O1 및 non-O139를 대상으로 하여 콜레라 독소, 콜레라 독소 유전자, 용혈소, 그리고 혈구응집소 등이 병독인자 분포를 알아보았다. 시험된 65균주 중 용혈소만 생산하는 균은 29균주였고, 용혈소와 혈구 응집소를 생산하는 것은 65균주 중 36 균주였다. 용혈소, 콜레라 독소 및 유전자, 그리고 혈구응집소 모두를 가지고 있는 것은 환경에서 분리된 O37형 한 균주이었다. 한편 첨가한 당농도에 따른 혈구응집소 억제시험에서, 1% 이하의 mannose 와 galactose에서 응짐이 억제된 것은 환경분리균주 47 균주 중에서 26균주로 내혈구응집소나 외혈구응집소가 비슷한 비율로 분포하였고, 반면 환자분리균주는 18균주 중에서 5균주가 외혈구응집소의 비율이 훨씬 높았다. 따라서 V.cholerae non-1 및 non-O139의 용혈소가 주독소로 병독인자 분포는 다양하게 나타났다. 콜레라 독소가 유일한 병독이자라고 인식하기는 어려웠고 여러 가지 인자들이 복합적으로 작용될 것으로 생각되었다. 특히 환경분리주 O37 형에서 콜레라 독소 생성윤이 발견된 것을 향후 역학적인 측면에서 많은 연구가 되어야 할 것으로 사료되었다.

• Journal of Microbiology and Biotechnology
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• 제25권1호
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• pp.98-108
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• 2015

Staphylococcus aureus is an important foodborne pathogen that causes diverse diseases ranging from minor infections to life-threatening conditions in humans and animals. To further understand its pathogenesis, the genome of the strain S. aureus FORC_001 was isolated from a contaminated food. Its genome consists of 2,886,017 bp double-stranded DNA with a GC content of 32.8%. It is predicted to contain 2,728 open reading frames, 57 tRNAs, and 6 rRNA operons, including 1 additional 5S rRNA gene. Comparative phylogenetic tree analysis of 40 complete S. aureus genome sequences using average nucleotide identity (ANI) revealed that strain FORC_001 belonged to Group I. The closest phylogenetic match was S. aureus MRSA252, according to a whole-genome ANI (99.87%), suggesting that they might share a common ancestor. Comparative genome analysis of FORC_001 and MRSA252 revealed two non-homologous regions: Regions I and II. The presence of various antibiotic resistance genes, including the SCCmec cluster in Region I of MRSA252, suggests that this strain might have acquired the SCCmec cluster to adapt to specific environments containing methicillin. Region II of both genomes contains prophage regions but their DNA sequence identity is very low, suggesting that the prophages might differ. This is the first report of the complete genome sequence of S. aureus isolated from a real foodborne outbreak in South Korea. This report would be helpful to extend our understanding about the genome, general characteristics, and virulence factors of S. aureus for further studies of pathogenesis, rapid detection, and epidemiological investigation in foodborne outbreak.

• 한국가금학회지
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• 제48권4호
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• pp.327-335
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• 2021

리메렐라 아나티페스티퍼 감염증은 오리와 거위에서 섬유소성 심막염, 간주위염증, 기낭염, 건락성난관염, 뇌막염을 특징으로 하는 급성 또는 만성 패혈증이다. 이 균은 혈청형 또는 분리주별로 병원성에 큰 차이가 나타나는 것으로 알려져 있다. 그럼에도 불구하고 지금까지 이러한 다양한 병원성과 그 이유에 대한 연구는 거의 이루어지지 않았다. 본 연구에서는 리메렐라 아나티페스티퍼의 병원성과 serum resistance 상관성을 구명하였다. 우리는 다양한 분리원으로부터 확보한 130주의 균주를 대상으로 serum resistance 특성을 분석하였다. 건강한 오리 인후두에서 분리된 균주들은 혈청에 대한 감수성이 높은 반면에 전신감염을 일으킨 균주들은 강한 serum resistance를 보였다. 또한 우리는 이러한 혈청의 살균효과가 혈청내 보체 성분에 의해 유도됨을 확인하였다. 강한 serum resistance를 유발하는 세균의 표면 유전자와의 관련성을 조사한 결과, 외막 단백질의 AS87_09335, AS87_00480, AS87_05195 유전자가 serum resistance와 관련 있음을 알 수 있었다. 본 연구 결과로 serum resistance 특성이 리메렐라 아나티페스티퍼의 병원성 결정 요소 중 하나라는 것을 확인하였다.