• 대한수의학회지
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• 제57권1호
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• pp.9-15
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• 2017

To construct a novel vaccine candidate against bovine enterotoxigenic Escherichia coli (ETEC), FanC, the major subunit of K99 fimbriae adhesion, was inserted into secretion plasmid pYA3560 containing a ${\beta}-lactamase$ secretion system. This was then transformed into ${\Delta}asd$ ${\Delta}crp$ Salmonella (S.) Typhimurium and designated as JOL950. Secretion of recombinant fanC fimbrial antigens was confirmed by immunoblot analysis. Groups of mice were inoculated with single or double doses of JOL950. Another group was used as a negative control. Compared to control mice, all immunized mice had significantly higher levels (p < 0.05) of serum immunoglobulin (Ig)G, and secretory IgA against FanC. The IgG2a and IgG1 titer assays revealed that immunization highly induced IgG2a compared to that of IgG1, indicating that T helper-1- related cell-mediated immune responses may be elicited by JOL950. The results show that both systemic and mucosal immunities against selected fimbrial antigens of bovine ETEC expressed by a live attenuated S. Typhimurium strain are prominently produced in mice immunized with JOL950 via an oral route.

• Journal of Microbiology and Biotechnology
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• 제27권9호
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• pp.1664-1669
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• 2017

Gamma-aminobutyric acid is a precursor of nylon-4, which is a promising heat-resistant biopolymer. GABA can be produced from the decarboxylation of glutamate by glutamate decarboxylase. In this study, a synthetic scaffold complex strategy was employed involving the Neurospora crassa glutamate decarboxylase (GadB) and Escherichia coli GABA antiporter (GadC) to improve GABA production. To construct the complex, the SH3 domain was attached to the N. crassa GadB, and the SH3 ligand was attached to the N-terminus, middle, and C-terminus of E. coli GadC. In the C-terminus model, 5.8 g/l of GABA concentration was obtained from 10 g/l glutamate. When a competing pathway engineered strain was used, the final GABA concentration was further increased to 5.94 g/l, which corresponds to 97.5% of GABA yield. With the introduction of the scaffold complex, the GABA productivity increased by 2.9 folds during the initial culture period.

• Applied Biological Chemistry
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• 제48권3호
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• pp.222-227
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• 2005

특수미인 거대배아미와 유색미의 발아처리에 의한 항돌연변이 활성의 변화를 평가하고자, 70% 에탄올 추출물이 in vitro에서 산화적 손상에 의한 DNA strand scission을 억제하는 효과와 함께 E. coli 및 V79 배양세포에 화학적으로 유발된 돌연변이에 대한 억제효과를 측정하였다. Mitomycin C로 유발된 돌연변이에 대한 억제활성을 E. coli에서 SOS chromotest로 조사한 결과, 활성은 발아유색미(40.4%) > 발아거대배아미(37.1%) > 무발아유색미(35.5%) > 발아현미(15.7%) > 무발아거대배아미(14.0%) > 무발아현미(0.8%)의 순서였다. Mitomycin C가 유도한 DNA strand scission에 대한 억제 효과는 무발아유색미 > 무발아거대배아미 > 발아유색미 > 발아현미 > 무발아현미 > 발아 거대배아미로 나타났다. V79 세포주에서 4-NQO로 유도된 6-TG 저항성 colony의 형성을 저해하는 활성을 지표로 항돌연변이 활성을 조사한 결과, 발아거대배아미(53.2%) > 무발아유색미(40.0%) > 무발아현미(21.2%) > 발아현미(14.4%) > 무발아거대배아미(0.23%)의 순서로 돌연변이를 저해하였는데, 발아유색미는 돌연변이를 촉진하는 것으로 나타났다(-69%).

• 한국식품위생안전성학회지
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• 제12권3호
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• pp.188-194
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• 1997

The growth inhibition effect of Orally administrated yogurt ACE and Metchnikoffupon E. coli O157:H7 and S. typhimurium inoculated into gastric lumen of rabbits was in vestigated. The rabbits challenged with each 1 $m\ell$ of suspension containing 108 CFU/$m\ell$ of the pathogens were divided into 4 groups by the interval of yogurt administration: A group; preadministrated 7 days before inoculation of the pathogens and fed daily; B group; administrated daily after inocjlation of the pathogens, C group; administrated every 3 days after inoculation of the pathogens; Control group, not fed after inoculation of the pathogens. Each 3 $m\ell$ of yogurt containing 109 CFU/$m\ell$ was orally administrated into rabbits. All yogurt administrated groups (A, B, c) chowed growth ingibition effect on E. coli O157:H7 in one day after inoculation of the pathogen by the level of 0.8~1.0 log CFU/g, compared with the result differences between the control group and the yogurt administrated groups. In the control group after 5 days of inoculation, the number of colonized pathogens was 105~106 CFU/g, whereas 103~104 CFU/g was detected in the yogurt administrated groups. After 10 days of inoculation, the viable pathogen number per gram (g) of the rabbit feces was 103 CFU/g in the control group, whereas the number below 101 CFU/g was detected in the group A, and 102 CFU/g in the control group, B and C. The growth inhibition effect of yogurt administration on E. coli O157:H7 was highly increased in the order of A, B, and C group. The same effect on S. typhimurium was observed at the level of 2 log CFU/g in the Metchnikoff yogurt administrated groups, compared with the control group result in one day after inoculation of the pathogen. In 7 days after inoculation of the pathogen, the viable number was increasingly decreased, and finally after 15 days no viable cell of S. typhimurium was discharged into the fecal samples in the group A, and the mean level of 10* CFU/g was detected in the group B, but there was no growth inhibition effect in the group C. The growth inhibition effect on S. typhimurium was observed at the same level of viable cell number between the yogurt ACE administrated groups and the control group in 5 days after inoculation. But, after 10 days of inoclation the viable cell number was started to decrease, and the viable cell of S. typhimurium was not discharged from rabbit intestinal contents after 15 days of inoculation in the yogurt ACE administrated groups. In such a case that yogurt was administrated in order to prevent the pathogens, pre-administration on a daily basis one week before inoculation of the pathogens exerted considerable effect in growth inhibition. In comparison with two kinds of yogurt tested in this study, the growth inhibition effect on two kinds of pathogens was observed more highly in the Metchnikoff administated group than the ACE administrated group.

• 한국식품과학회지
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• 제32권1호
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• pp.218-224
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• 2000

분자량이 상이한 세 종류의 키토산의 항균활성을 E. coli O157 : H7, S. aureus 및 C. albicans 균주를 이용하여 측정, 분석하였다. E. coli O157 : H7와 S. aureus에 대해서는 분자량 10,000인 키토산이 가장 강한 항균활성을 보였으며 C. albicans에 대해서는 6량체의 키토산 올리고당이 가장 강한 활성을 나타내었다. 키토산 첨가농도는 E. coil O157 : H7와 S. aureus의 경우 0.1 mg/mL의 농도에서, C. albicans의 경우는 chitohexaose 1 mg/mL의 농도에서 항균활성이 가장 높았다. 모든 키토산 처리구에서 미생물 사멸 속도는 키토산 처리 1시간 이내에서 가장 높게 나타났으며 그 이후로는 점차 낮은 속도를 보였다. 사멸되었거나 파손된 미생물 세포로부터 유래되는 단백질, 핵산물질 및 $Ca^{2+}$ 량은 키토산 처리 시간 이내에 가장 많았으며 ${\beta}-galactosidase$ 활성도 같은 시간대에서 가장 빠른 속도로 중대되는 것으로 나타났다. S. aureus에 대한 세포막 손상 정도를 측정하여 본 결과 전체 미생물균체중 약 10%에 상당하는 균수가 막손상을 가져 왔다. 따라서, 키토산은 고유의 양이온성 성질을 이용하여 미생물의 세포벽과 세포막에 결합하여 그 결과로 세포 내 물질의 세포 외로의 유출내지는 세포막 대사의 저해 등의 효과를 나타냄으로써 항균활성을 나타내는 것으로 추측되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제19권11호
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• pp.1665-1670
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• 2006

The objective of this research was to provide the characterization and method for producing anti-E. coli O157:H7 antibodies in egg-laying hens and to determine if the antibody can restrain the proliferation of E. coli O157:H7 in-vitro. Selected antigenic fractions (whole cell, outer membrane protein and lipopolysaccharide (LPS)) from E. coli O157:H7 were injected to hens in order to produce anti-E. coli O157:H7 antibodies. The immune response and the egg yolk antibodies of laying hens against the whole cell, outer membrane protein and LPS antigens were monitored by ELISA. The level of antibodies against whole cell antigen monitored through ELISA sharply increased after the initial immunization, and it was found to be maximum on day 49 however, the level was maintained up to day 70. Antibodies (5 mg/ml) directed against the whole cell inhibited E. coli proliferation 10-13 times more than outer membrane protein or LPS. The antibody response against the whole cell antigens appeared to have higher activity in restraining the proliferation of E. coli O157:H7 than antibody against outer membrane protein or LPS. Results reflected that increasing the IgY's in the egg yolk could prevent greater economic losses due to human and animal health from pathogenic bacteria i.e. E. coli O157:H7.

• Journal of Microbiology and Biotechnology
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• 제30권7호
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• pp.974-981
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• 2020

Sequence type 410 (ST410) of Escherichia coli is an extraintestinal pathogen associated with multi drug resistance. In this study, we aimed to investigate the horizontal propagation pathway of a high-risk clone of E. coli ST410 that produces Klebsiella pneumoniae carbapenemase (KPC). blaKPC-encoding E. coli and K. pneumoniae isolates were evaluated, and complete sequencing and comparative analysis of blaKPC-encoding plasmids from E. coli and K. pneumoniae, antimicrobial susceptibility tests, polymerase chain reaction, multilocus sequence typing, and conjugal transfer of plasmids were performed. Whole-genome sequencing was performed for plasmids mediating KPC-2 production in E. coli and K. pneumoniae clinical isolates. Strains E. coli CPEc171209 and K. pneumoniae CPKp171210 were identified as ST410 and ST307, respectively. CPEc171209 harbored five plasmids belonging to serotype O8:H21, which is in the antimicrobial-resistant clade C4/H24. The CPKp171210 isolate harbored three plasmids. Both strains harbored various additional antimicrobial resistance genes. The IncX3 plasmid pECBHS_9_5 harbored blaKPC-2 within a truncated Tn4401a transposon, which also contains blaSHV-182 with duplicated conjugative elements. This plasmid displayed 100% identity with the IncX3 plasmid pKPBHS_10_3 from the K. pneumoniae CPKp171210 ST307 strain. The genes responsible for the conjugal transfer of the IncX3 plasmid included tra/trb clusters and pil genes coding the type IV pilus. ST410 can be transmitted between patients, posing an elevated risk in clinical settings. The emergence of a KPC-producing E. coli strain (ST410) is concerning because the blaKPC-2-bearing plasmids may carry treatment resistance across species barriers. Transgenic translocation occurs among carbapenem-resistant bacteria, which may spread rapidly via horizontal migration.

• 미생물학회지
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• 제32권1호
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• pp.40-46
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• 1994

Polychlorinaed biphenyls(PCBs) 와 biphenyl을 분해하는 Pseudomonas sp. DJ-12에서는 그 초기 분해과정에 pcb ABCD 유전자들이 관여하고 있음이 밝혀졌다. 그 중 pcbCD와 pcdD 유전자를 E. coli XL1-Blue에 클로닝하여 E. coli CU103 과 CU105 균주를 각각 제조하였다. E. coli CU103은 2,3-dehydroxybuphenyl dioxygenase(2,3-DHBP)와 meta-cleavage compound(MCP) hydrolase를 생성하여 2,3-dihydroxybiphenyl을 benzoate로 변환시켜 주었다. E. coli CU1 과 CU103 에서 pcbC 유전자의 산물인 2,3-DHBP dioxygense의 활성도는 Pseudomonas sp. DJ-12에서 보다 약 17배 높았으며, E. coli CU105에서 pcbD의 산물인 MCP hydrolase는 약 3배 더 높게 나타났다.

• Food Quality and Culture
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• 제2권1호
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• pp.55-60
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• 2008

This study examined the effects of lactic acid spray, hot water spray, or their combined treatment, as well as the effects of acidified sodium chlorite (ASC), for the decontamination of Escherichia coli on beef carcass surfaces using a commercial intervention system. With this system, the effects of 2 or 4% lactic acid (v/v), hot water ($89{\pm}1^{\circ}C$), or their combined treatment, were examined in terms of reducing inoculated E. coli. ASC (266 ppm), which was adjusted to pH 2.5 using acetic acid or citric acid, was applied using a hand-held spray system. When the beef carcasses were treated with 2 or 4% lactic acid for 10.4 s, less than 1 log reductions of inoculated E. coli were observed. A hot water spray treatment for 9.8 s resulted in a 2.1 log reduction of inoculated E. coli. However, when the hot water was followed with either 2 or 4% lactic acid, no difference in E. coli reduction was found between the hot water alone or the combined treatment with lactic acid. When ASC was adjusted to pH 2.5 with acetic acid and citric acid, 3.8 and 4.1 log reductions of E. coli were observed, respectively. Overall, the lactic acid spray treatment was least effective, and the ASC treatment was most effective, for the E. coli decontamination of beef carcasses. Therefore, these data suggest that ASC would be a more effective intervention against E. coli than most of the methods currently being used. However, more research is required to evaluate the effects of ASC on other organisms, as well as to identify application methods that will not affect meat quality.

• Journal of Microbiology and Biotechnology
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• 제27권1호
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• pp.67-71
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• 2017

This study examined the antimicrobial activity of flaxseed meal extract (FME) against Staphylococcus aureus and Escherichia coli O157:H7 inoculated on red mustard. With the treatment of 0.7% FME for 3 min, the reduction levels of S. aureus and E. coli O157:H7 populations were 1.23 and 1.83 log CFU/g, respectively. In addition, the combined treatment of 0.7% FME at $50^{\circ}C$ for 3 min reduced the populations of the pathogenic bacteria by 2.28 and 2.41 log CFU/g, respectively. The color and the vitamin C content were not significantly different between treatments. Thus, FME can be used as a novel antimicrobial agent in fresh-cut vegetables.