• 한국식품과학회지
• /
• 제31권1호
• /
• pp.183-188
• /
• 1999

국내 식육중 Y. enterocolitica의 분포 조사 및 분리균의 특성을 조사하기 위하여 4월부터 11월사이에 상, 하반기로 나누어 소고기, 돼지고기, 닭고기 463건을 서울, 대전, 광주, 부산에서 구입하여 실험하였다. 전체 식육중 17.5% (81건)에서 Y. enterocolitica가 분리되었으며 닭고기(26.0%)가 가장 많이 오염되어 있었다. 분리율은 계절에 따라 차이를 보였는데 하반기에 수거한 돼지고기와 닭고기에서 상반기보다 2배이상 높은 균 분리율을 보였다. 항생제 감수성 실험결과 대부분의 분리균은 carbenicillin, ampicillin, erythromycin, penicillin, bacitracin에 대해 내성을 나타내는 반면 polymyxin B, kanamycin, trimethoprim/sulfamethoxazole, ciprofloxacin, tetracycline, nalidixic acid, gentamicin등에 감수성을 나타내었다. 분리된 Y. enterocolitica의 혈청형은 serotype O:5가 주종이었고 일본 및 유럽 등지에서 많이 분리되어지는 O:9는 분리되지 않았다. PCR 실험결과 81개의 분리균주중 8균주(10%)가 병원성을 갖고있는 것으로 밝혀졌는데 그 중 6균주가 돼지고기에서 발견되었다. 그리고 돼지고기 분리균주중 병원성이 없는 것으로 널리 알려져 있는 serotype O:5가 PCR 양성반응으로 병원성을 보여 이전 연구들과 상반된 결과를 나타낸 것에 대해서는 더 연구해야할 과제로 남아 있다.

• 대한의생명과학회지
• /
• 제8권3호
• /
• pp.107-113
• /
• 2002

Enterohemorrhagic Escherichia coli (EHEC) strains of serotype O157:H7 have been shown to colonize the intestinal epithelial cell by the attaching and effacing (AE) mechanism. The AE lesion is mediated by an intimin, of which production and expression are controlled by a 3-Kb eaeA gene located EHEC chromosomal DNA. If the eaeA gene is mutated, EHEC O157:H7 strains lose capacity of adhesion to intestinal epithelial cells. In this study, a 891 bp of the 3'-end region of a gamma intimin was amplified by polymerase chain reaction (PCR). The PCR product was inserted into pSTBlue-1 cloning vector and transformed into DE3 (BL21) competent cell. After plasmid mini-preparation and restriction enzyme digestion of eaeA/891-pSTBlue-1 vector, target eaeA gene was re-inserted into pET-28a expression vector and was transformed. Then the expression of recombinant eaeA/891 (891 bp) gene was induced by isopropyl-$\beta$-D-thiogalactopyranoside (IPTG). The expression of the 40-KDa recombinant protein was identified in SDS-PAGE and confirmed by immunoblotting using the His.Tag$^{\circledR}$ and T$_{7}$.Tag$^{\circledR}$ monoclonal antibody. This recombinant protein expressed by eaeA gene could be applied in further studies on the mechanisms of E. coli O157:H7 infection and the development of recombinant vaccine.

• Journal of Microbiology and Biotechnology
• /
• 제23권5호
• /
• pp.731-737
• /
• 2013

Seventy-four Shiga toxin-producing Escherichia coli (STEC) isolates belonging to the serotype O91:H21 were isolated from 1,643 asymptomatic human carriers in a STEC outbreak at Gwangju in Korea. Although the isolates did not cause any symptoms, all of them produced Shiga toxins 1 (Stx1) and 2 (Stx2). In order to determine why these strains cause no symptoms, we explored the differences in virulence potential between the asymptomatic STEC O91:H21 isolates and symptomatic STEC O91:H21 strains (ATCC 51435 and ATCC 51434). The asymptomatic STEC O91:H21 isolates showed strongly reduced cytopathic effects compared with the symptomatic strains when intact bacterial cells were used as an inoculant. Moreover, we found a reduced adherence phenotype when testing asymptomatic strains on HeLa cells. Real-time quantitative PCR results suggest that transcriptional repression of the genes encoding type-1 fimbriae occurs in the asymptomatic isolates but not in the symptomatic strains.

• 대한의생명과학회지
• /
• 제28권2호
• /
• pp.127-136
• /
• 2022

Uropathogenic Escherichia coli (UPEC) is main causative agent of urinary tract infections. They are classified based on various types of O antigen. UPEC strains commonly possess many genes encoding virulece-associated factors. E. coli strains are generally divided into four main phylogenetic groups. The virulence factor (VF) profiles of UPEC are related with their O-serogroups in each strains. A total of 681 strains of UPEC clinical isolates were collected from Korean healthcare facility (1989: 123 strains and 2010-2014: 558 strains). The UPEC clinical isolates were analyzed by polymerase chain reaction (PCR) methods. A total of 14 O-serotypes (O1, O2, O4, O6, O7, O8, O15, O16, O18, O21, O22, O25, O75 and O83), 6 virulence factors (papC, fimG/H, sfaD/E, hly1, cnf1 and usp) and phylogenetic groups were identified. The most prevalent O-serogroups were O6 (11.1%) in 1989 UPEC strains and O25 (21.0%) in 2010-2014 UPEC strains. The identified VFs, phylogenetic groups in 1989 UPEC strains and 2010-2014 UPEC strains were fimG/H and B2 group. In this study, O6 serotype was revealed the close relationships with VFs. Also, the distribution of prevalence O-serogroups of UPEC has been changed from O6 to O25 and virulence of UPEC strains was increased during past twenty-one years.

• 한국식품조리과학회지
• /
• 제27권4호
• /
• pp.17-26
• /
• 2011

본 연구는 지유 에탄올 추출물의 항균 및 항돌연변이 활성을 측정하여 새로운 기능성 소재로서의 기초자료를 얻고자 실시하였다. E. coli, E. coli O157:H7, P. aeruginosa, S. Typhimurium, L. monocytogenes, B. cereus, S. aureus의 7가지 주요 식품위해성 세균에 대한 항균활성을 검증하기 위해 paper disc diffusion assay 및 최소저해농도를 측정하였으며 24시간 동안 균의 생육억제도를 측정하였다. Paper disc assay 결과 E. coli와 E. coli O157:H7을 제외한 5가지 균에 대한 지유 에탄올 추출물의 뚜렷한 clear zone이 확인되었다. Micro-well dilution법으로 확인한 최소저해농도의 범위는 E. coli와 E. coli O157:H7을 제외한 5가지 균에 대해서 0.625~2.5 mg/mL로 나타났으며 생육억제도 실험결과도 최소 저해농도 결과와 일치하였다. Salmonella Typhimurium TA100을 이용한 Ames test 결과, 5 mg/plate의 농도에서 직접 돌연변이원인 sodium azide와 4-NQO에 대한 지유 에탄올 추출물의 항돌연변이 활성이 각각 72.42와 89.85%로 나타나 지유 에탄올 추출물의 우수한 항돌연변이 활성을 확인하였다. 본 연구를 통해 지유 에탄올 추출물이 주요 식품위해성 세균들에 대한 우수한 항균성과 직접돌연변이원에 대한 높은 항돌연변이 활성을 나타내어 천연물 유래 생리활성 소재로 이용될 수 있는 가능성을 보여주었다.

• 한국미생물·생명공학회지
• /
• 제31권4호
• /
• pp.334-341
• /
• 2003

2001년 경북지역 콜레라 유행시 설사환자에서 V. cholerae O1 El Tor형 90주를 분리하였다. 분리균을 대상으로 ctxA, tcpA, hlyA gene에 대한 multiplex-PCR 시험에서는 분리균 모두에서 302, 223, 471 bps크기의 DNA 증폭산물 band를 확인하였다. ctxA 및 ctxB gene 부위의 유전자 염기서열 비교에서 분리균과 GenBank에 수록된 균간의 유형의 차이를 보였다. PFGE typing 실험에서는 분리균 모두에서 동일한 amplicon 단편을 나타내었다. 또한, 2002년 8월부터 10월까지 콜레라균 서식가능성 규명을 위해 경북 동해안 일대에서 plankton 시료채취 및 V. cholerae O1 및 V. cholerae O139의 rfb 및 CT gene 검출을 위한 multiplex-PCR 확인실험에서는 ctxA gene의 DNA band는 일부 검출되었으나, V. cholerae O1 및 V. cholerae O139는 분리되지 않았다. 험에서 ctxA gene DNA band는 검출되었으나, V. cholerae O1 및 V. cholerae O1는 분리되지 않았다.

• Journal of Microbiology and Biotechnology
• /
• 제31권9호
• /
• pp.1191-1199
• /
• 2021

Enteropathogenic Escherichia coli (EPEC), which belongs to the attaching and effacing diarrheagenic E. coli strains, is a major causative agent of life-threatening diarrhea in infants in developing countries. Most EPEC isolates correspond to certain O serotypes; however, many strains are non-typeable. Two EPEC strains, EPEC001 and EPEC080, which could not be serotyped during routine detection, were isolated. In this study, we conducted an in-depth characterization of their putative O-antigen gene clusters (O-AGCs) and also performed constructed mutagenesis of the O-AGCs for functional analysis of O-antigen (OAg) synthesis. Sequence analysis revealed that the occurrence of O-AGCs in EPEC001 and E. coli O132 may be mediated by recombination between them, and EPEC080 and E. coli O2/O50 might acquire each O-AGC from uncommon ancestors. We also indicated that OAg-knockout bacteria were highly adhesive in vitro, except for the EPEC001 wzy derivative, whose adherent capability was less than that of its wild-type strain, providing direct evidence that OAg plays a key role in EPEC pathogenesis. Together, we identified two EPEC O serotypes in silico and experimentally, and we also studied the adherent capabilities of their OAgs, which highlighted the fundamental and pathogenic role of OAg in EPEC.

• 한국식품위생안전성학회지
• /
• 제12권4호
• /
• pp.354-360
• /
• 1997

This study was intended that the biochemical patterns, bioserological characteristics, resistance of antibiotics, and transferable resistance patterns of 35 Dscherichia coli strains from 79 fish and shellfish samples in marine markets from August to October, 1995. The Standard plate count, coliforms and fecal coliforms were also counted in the 79 cases and analysed the correlationship each other. Geometric means of Standard plate count in seawater fish, shellfish, mollusca and crustacean were 1.4$\times$105 CFU/g, 4.0$\times$105 CFU/g, 2.4$\times$105 CFU/g, 4.7$\times$105 CFU/g, and those of coliforms were 1.3$\times$103 CFU/g, 4.8$\times$103 CFU/g, 8.9$\times$102 CFU/g, 5.8$\times$103 CFU/g. There were no fecal coliforms in the fish and mollusc. However, the geometric means of coliforms in the shellfish and crustacean (1.1$\times$101 CFU/100g, 10 CFU/100 g) were less than those of fish and mollusca. The important biochemical characteristics of E. coli distinguished from the shellfish and crustacean were motility, ornithine decarboxylase, mucate, esculin. The fermentative properties of E. coli were also sucrose, salicin, sorbitol, and raffinose. Of 35 isolates of E. coli, 13 strains (37.1%) showed the pathogenic O antisera, which were O:27 3 strains (23.1%), ):159 2 strains (15.4%) and ):148, O:119, O:142, O:158, O:136, O:18, O:128, and O:168 1 strain (7.7%),respectively.

• 한국동물위생학회지
• /
• 제20권4호
• /
• pp.359-370
• /
• 1997

This study was carried out to Investigate the biochemical characteristics, antibiotic susceptibility, serogroups and pili producibility test of enterotoxigenic Escherichia coli(ETEC) isolated from piglets with diarrhea in Kangwon province from March to October 1996. 1. Sixty eight E coli strains were isolated from 72 piglets with diarrhea and the biochemical and cultural reaction were compared with the classification criteria of Edwards and Ewing. 2. The serogroups of 26 isolates were classified as 08 : K87 6(8.8%), O20 : K1O1 4(5.9%), O141 : K85 4(5.9%), 09 : K103 : P987 3(4.4%), O45 : K 2(2.9%) 0139 : K82 2(2.9%), O64 : $K^{-}$2(2.9%), O149 : K91 1(1.5%), O157 : K88ac 1(1.5%) and O115 : $K^{-}$1(1.5%), respectively. 3. In antibiotic susceptibility test, the isolates showed high susceptible to Ak, Eno, Na, Gm, Am and Km, whereas resistance to Tc, Sm and Cf. 4. Sixty one strains(89.7%) of 68 I coli Isolates were resistant to one or more drugs. The isolates resistant to 2 and 3 or more drugs were 60.3% and 19.1%, respectively. Amog the 16 multiple resistant patterns, Sm Tc(11.5% ), Cf Sm Tc(11.5% ), Cf Cp Sm Su Tc(9.8% ) and Cf Cp Sm Su Tc(8.2%) patterns were frequently observed. 5. MRHA of guinea pig erythrocytes was detected in 9 out of 26 OK serotype and 9 out of 42 unidentified serotypes. MRHA titers of serotypes showed from 16 to 32 in O141 : K85 and no titers in O139 : K82. 6. By the GM1 ganglioside ELISA, $\beta$-, $\alpha$-, and $\gamma$-hemolysin producing strains was detected as 36, 6, and 5 from heat labile enterotoxin(LT) of 47 ETEC, respectively. The distribution of LT toxin from 112 isolates was showed $\beta$- hemolysin, 2 isolates $\alpha$-hemolysin and 3 isolates $\gamma$-hemol-ysin from 26 OK serotypes.

• Journal of Microbiology and Biotechnology
• /
• 제13권4호
• /
• pp.509-516
• /
• 2003

A model system for the immnunochemical detection of Escherichia coli O157:H7 using a combined immunomagnetic separation (IMS) and test-strip liposome immunoassay (LIA) procedure was developed. Immunomagnetic beads coated with anti-E. coli O157 IgG antibodies were used to separate the E. coli O157 (including the H7 serotype) from culture. Immunoliposomes, whose surface was conjugated to goat anti-E. coli O157:H7 IgG and which encapsulated the marker dye, sulforhodamine B, were used as a detection label. The test strip, onto which antibodies to goat IgG were immobilized, was the immunosensor capturing immunoliposomes that did not bind to E. coli O157:H7 on the immunomagnetic bead-E. coli O157:H7 complexes. In experiments, pure cell culture suspensions of $10^5 E.$ coli O157:H7 organisms per ml produced a measurable signal inhibition, whereas a weak yet detectable signal inhibition occurred with $10^3CFU/ml$. The inhibition signals increased, when the incubation time for IMS was extended to 90 min and higher IgG-tag density (0.4mol%) was used on the liposomes. With 0.2 and 0.4mol% IgG-tagged liposomes, the IMS-LIA procedure showed more improved signal inhibitions than those of a direct (no IMS) LIA. The combined assay, which measures the instantaneous signal from immunoliposomes, can be completed within 90 min, making it significantly faster than conventional plating methods and enzyme-linked immunosorbent assay (ELISA). Accordingly, it is quite feasible to use the combined immunoassay format of IMS and dye-loaded immunoliposomes for the detection of E. coli O157:H7.