• 한국식품과학회지
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• 제52권1호
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• pp.11-18
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• 2020

발효식품의 우점종 Enterococcus 속 박테리아는 식품발효에 중요한 역할을 담당할 뿐만 아니라 사람과 가축의 프로바이오틱스로 사용되는 긍정적 측면을 가지고 있지만, 균혈증, 심내막염 등의 병원감염을 일으키는 병원균으로도 알려져 있다. 또한 여러 항생제에 대한 내성균주와 부착분자, 선모, 용혈소 등의 독성인자 보유 균주들이 발견되고 있어 식품용 미생물 및 프로바이오틱스로서의 적합성에 의문이 제기되고 있다. 본 총설에서는 우선 Enterococcus의 긍적적 및 부정적 측면에 대한 정보를 제공하여 논란이 되고 있는 문제점을 제시하였고, 유전체 연구를 통하여 부정적인 측면을 보유하지 않은 식품산업에서 활용할 수 있는 균주 선발 방향을 검토하였다. 또한 우리나라 전통발효식품용 종균개발 현황과 신규 식품용 미생물 인허가 제도를 검토하여 문제점을 파악하였다. 결론으로 Enterococcus 연구결과에 근거 우리나라 신규 식품용 미생물의 안전성 평가 방향성을 제시하였다.

• The Plant Pathology Journal
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• 제15권3호
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• pp.137-143
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• 1999

A novel chromosomal gene tagging technique using a specific fragment of the fatty acid desaturase-like open reading frame (des-like ORF) from the tox-argK gene cluster of Pseudomonas syringae pv. phaseolicola was developed to identify Xanthomonas spp.released into the environment as biocontrol agents. X. campestris pv. convolvuli FB-635, a pathogen of Convolvulus arvensis L., (bindweed), was chosen as the organism in which to develop and test the system. A 0.52 kb DES fragment amplified from P. syringae pv. phaseolicola C-199 was inserted into pGX15, a cosmid clone containing a 10.3 kb Eco RI-HindIII fragment derived from the xanthomonadin biosynthetic gene cluster contained in plasmid pIG102, to create a pigG::DES insertion. The 10.8 kb EcoRI-BamHI fragment carrying the pigG:: DES insertion was cloned into pLAFR3 to generate pLXP22. pLXP22 was then conjugated into X. campestris pv. convolvuli FB-635 and the pigG::DES insertion integrated into the bacterial chromosome by marker exchange. Rifampicin resistant, tetracycline sensitive, starch hydrolyzing, white colonies were used to differentiate the marked strain from yellow pigmented wild-type ones. PCR primers specific for the unique DES fragment were used for direct detection of the marked strain. Result showed the marked strain could be detected at very low levels even in the presence of high levels of other closely related or competitive bacteria. This PCR-based DES-tagging system provides a rapid and specific tool for directly monitoring the dispersal and persistence of Xanthomonas spp.released into the environment.

• 한국식물병리학회지
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• 제3권3호
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• pp.203-209
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• 1987

Pseudomonas solanacearum의 병원성균주 및 비병원성균주를 담배의 뿌리에 접종하여 그 잎과 줄기, 뿌리에서 P. solanacearum과 Erwinia carotovora subsp. carotovora, Escherichia coli에 대한 항균물질을 분리하였다. 담배즙액을 TLC plate에 발전시킨 결과 비병원성균주에 접종된 담배에서는 $R_f$ 0.6 부근에서, 병운성균주에 접종된 담배에서는 $R_f$ 0.9 부근에서 각각 항균물질을 분리할 수 있았다. 그러나 고압살균된 담배즙액배지에 병원성균주 및 비병원성균주를 3일간 배양한 배양여액에서는 항균물질의 생성이 인정되지 않았다. 비병원성균주 및 병원성균주에 접종된 담배잎에서는 무처리 담배에 비하여 peroxidase와 polyph-enoloxidase의 활성이 높았으나, 그 줄기와 뿌리에서는 효소활성의 차이가 없었다. 비병원성균주와 병원성균주로 처리된 담배 사이, 감수성품종인 BY4와 저항성품종 NC82 사이에도 두 효소의 활성과 동위효소형태의 차이가 없었다.

• Pediatric Infection and Vaccine
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• 제23권3호
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• pp.223-228
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• 2016

국내 Shigella 감염은 대부분 Shigella sonnei 에 의해 발생하나 드물게 Shigella flexneri 에 의한 집단 감염이 보고되고 있다. 항생제 사용률이 높은 국내에서 extended-spectrum ${\beta}-lactamase$ (ESBL) 생성 S. sonnei 감염에 대한 보고는 있었으나 ESBL을 생성하는 S. flexneri 에 대한 예는 지금까지 없었다. 저자들은 국내 한 어린이집에 다니는 소아 2명에게서 CTX-M-14 유형 ESBL 생성 S. flexneri type 2a 감염 증례를 경험하였으며 이는 국내에서 ESBL을 생성하는 S. flexneri 감염의 첫 증례이다. 앞으로 국내에서도 Shigella 감염 시 ESBL 균주의 가능성을 고려하고 적극적인 역학조사와 경험적 항생제 투여에 대한 신중한 선택이 필요할 수 있을 것으로 생각된다.

• 한국식품위생안전성학회지
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• 제35권2호
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• pp.103-108
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• 2020

최근 최소한으로 가공된 안전한 식품에 대한 소비자의 수요가 기하급수적으로 증가하고 있다. 이러한 이유로 많은 식품가공 업체에서는 식품안전을 강화하고 유통기한을 연장하기 위한 최소한의 가공공정 중 허들기술(hurdle technology)을 적용하고 있다. 한편, 연구에 따르면 식품에 함유된 병원균을 비활성화하기 위한 공정 및 방법들은 식중독세균들의 스트레스 적응 메커니즘을 촉발시켜 심지어 후속 치료로 부터 교차 보호를 준다. 또한, 항생제와 제초제 사용과 같은 일상적인 농장 관행은 항생제 내성을 가진 병원균의 생성을 초래할 수 있다. 이러한 항생제 내성 박테리아는 식품 처리과정과 관련된 스트레스에 내성을 가질 수 있고 가공 식품에서 생존할 수 있는 가능성을 높일 수 있다. 이 리뷰에서는 식품가공과 관련된 스트레스와 항생제 내성의 상관관계에 대해 논의한다. 또한, 항균성 화합물 및 기타 식품 처리 관련 스트레스에 대한 교차 보호 수단으로서 시그마 인자(sigma factors), SOS 반응 경로(SOS response pathways) 및 유출 펌프(efflux pumps)의 사용과 같은 분자유전학적 기작에 대해서도 논의한다.

• Asian Pacific Journal of Cancer Prevention
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• 제15권20호
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• pp.8883-8886
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• 2014

Background: Tetracycline is an antibiotic widely used for the treatment of Helicobacter pylori infection, but its effectiveness is decreasing due to increasing bacterial resistance. The aim of this study was to investigate the occurrence of 16S rRNA mutations associated with resistance or reduced susceptibility to tetracycline ofHelicobacter pylori by real-time PCR (RT-PCR) assays from culture. Materials and Methods: Tetracycline susceptibility and minimal inhibition concentration (MIC) was determined by the Epsilometer test (Etest) method. A LightCycler assay developed to detect these mutations was applied to DNA extracted from culture. The 16S rRNA of these isolates was sequenced and resistance-associated mutations were identified. From 104 isolates of H. pylori examined, 11 showed resistance to tetracycline. Results: LightCycler assay was applied to DNA extracted from 11 tetracycline-susceptible and 11 tetracycline resistance H. pylori isolates. In our study the sequencing of the H. pylori wild types in 16 s rRNA gene were AGA 926-928 with MIC (0.016 to $0.5{\mu}g/ml$), while the sequencing and MIC for resistant were GGA and AGC, (0.75 to $1.5{\mu}g/ml$), respectively. Also we found a novel mutation in 2 strains with $84^{\circ}C$ as their melting temperatures and exhibition of an A939C mutation. Conclusions: We conclude that real-time PCR is an excellent method for determination of H. pylori tetracycline resistance related mutations that could be used directly on biopsy specimens.

• Asian-Australasian Journal of Animal Sciences
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• 제15권5호
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• pp.751-756
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• 2002

A study was carried out to evaluate the incidences and causes of bovine mastitis in Tanzanian shorthorn zebu (Bos indicus) in the traditional sector and crossbred cows (Bos taurus${\times}$Bos indicus) in the dairy ranching sector, both found under the extensive range management system. Management practices were evaluated through a survey study using structured questionnaires. A total of 120 lactating cows (60 cows from each sector) were screened for the disease using the California Mastitis Test (CMT). Confirmatory tests used for infected cows included; the Direct Microscopic Somatic Cell Count (DMSCC), culture, bacteriological and biochemical laboratory assays. Survey results showed that management practices were generally very poor in both sectors with 84% of the surveyed herds being kept and milked under very unhygienic environmental conditions. The level of infection was higher in the crossbred cows (5% clinical and 38.3% sub-clinical mastitis) and lower in the zebu cows with only sub-clinical mastitis (23.3%). Crossbred cows had (p<0.05) higher somatic cell counts than zebu cows. The four highest-ranking bacterial isolates in order of importance were Staphylococcus aureus, Escherichia coli, Streptococcus agalactiae and Bacillus spp. It was concluded that bovine mastitis under the extensive management system in Tanzania was a result of poor management practices and that zebu cows were more resistant to the diseases than crossbred cows.

• Clinical and Experimental Pediatrics
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• 제60권7호
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• pp.221-226
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• 2017

Purpose: Escherichia coli sequence type (ST) 131, a multidrug-resistant clone causing extraintestinal infections, has rapidly become prevalent worldwide. However, the epidemiological and clinical features of pediatric infections are poorly understood. We aimed to explore the characteristics of ST131 Escherichia coli isolated from Korean children with urinary tract infections. Methods: We examined 114 uropathogenic E. coli (UPEC) isolates from children hospitalized at Chung-Ang University Hospital between 2011 and 2014. Bacterial strains were classified into STs by partial sequencing of seven housekeeping genes (adk, fumC, gyrB, icd, mdh, purA, and recA). Clinical characteristics and antimicrobial susceptibility were compared between ST131 and non-ST131 UPEC isolates. Results: Sixteen UPEC isolates (14.0%) were extended-spectrum ${\beta}-lactamase$ (ESBL)-producers; 50.0% of ESBL-producers were ST131 isolates. Of all the isolates tested, 13.2% (15 of 114) were classified as ST131. There were no statistically significant associations between ST131 and age, sex, or clinical characteristics, including fever, white blood cell counts in urine and serum, C-reactive protein, radiologic abnormalities, and clinical outcome. However, ST131 isolates showed significantly lower rates of susceptibility to cefazolin (26.7%), cefotaxime (40.0%), cefepime (40.0%), and ciprofloxacin (53.3%) than non-ST131 isolates (65.7%, 91.9%, 92.9%, and 87.9%, respectively; P<0.001 for all). ESBL was more frequently produced in ST131 (53.3%) than in non-ST131 (8.1%) isolates (P<0.01). Conclusion: ST131 E. coli isolates were prevalent uropathogens in children at a single medical center in Korea between 2011 and 2014. Although ST131 isolates showed higher rates of antimicrobial resistance, clinical presentation and outcomes of patients were similar to those of patients infected with non-ST131 isolates.

• Molecules and Cells
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• 제28권2호
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• pp.131-137
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• 2009

Plant defensins are small (5-10 kDa) basic peptides thought to be an important component of the defense pathway against fungal and/or bacterial pathogens. To understand the role of plant defensins in protecting plants against the brown planthopper, a type of insect herbivore, we isolated the Brassica rapa Defensin 1 (BrD1) gene and introduced it into rice (Oryza sativa L.) to produce stable transgenic plants. The BrD1 protein is homologous to other plant defensins and contains both an N-terminal endoplasmic reticulum signal sequence and a defensin domain, which are highly conserved in all plant defensins. Based on a phylogenetic analysis of the defensin domain of various plant defensins, we established that BrD1 belongs to a distinct subgroup of plant defensins. Relative to the wild type, transgenic rices expressing BrD1 exhibit strong resistance to brown planthopper nymphs and female adults. These results suggest that BrD1 exhibits insecticidal activity, and might be useful for developing cereal crop plants resistant to sap-sucking insects, such as the brown planthopper.

• The Plant Pathology Journal
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• 제16권6호
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• pp.312-317
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• 2000

The selected five plant growth-promoting rhizobacteria (PGPR) strains, WR8-3 (Pseudomonas fluorescens), WR8-6 (P. putida), WR9-9 (P. fluorescens), WR9-11 (Pseudomonas sp.), and WR9-16 (P. putida) isolated in the rhizosphere of watermelon plants were tested on their growth promotion and control effect against gummy stem rot of watermelon. Strains, WR8-3 and WR9-16 significantly increased stem length of watermelon, and there was a little increase in leaf area, fresh weight and root length when strains, WR8-3, WR9-9 and WR9-16 were treated. Generally, seed treatment was better for plant growth promotion than the soil drench, but there was no significant difference. Seed treatment and soil drench of each bacterial strain also significantly reduced the mean lesion area (MLA) by gummy stem rot, but there was no significant difference between the two treatments. At initial inoculum densities of each strain ranging from 10$^6\;to\;10^{15}$ cfu/g seed, approximately the same level of disease resistance was induced. But resistance induction was not induced at the initial inoculum density of 10$^3$ cfu/g seed. Resistance was induced by treating the strains, WR9-9, WR9-11 and WR9-16, on all of four watermelon varieties tested, and there was no significant difference in the decrease of gummy stem rot among varieties. Populations of the strains treated initially at log 9-10 cfu/g seed, followed with a rapid decrease from planting day to 1 week after planting, but the population density was maintained above log 5.0 cfu/g soil until 4 weeks after planting. Generally no or very weak in vitro antagonism was observed at the strains treated excepting WR9-11. Rifampicin-resistant bacteria which had been inoculated were not detected in the stems or leaves, which suggesting that the bacterium and the pathogens remained spatially separated during the experiment. This is the first report of rsistance induction in watermelon to gummy stem rot by PGPR strains.