• 대한수의학회지
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• 제27권2호
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• pp.245-251
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• 1987

A total of 145 strains of thermophilic Campylobacter spp. isolated from the fecal specimens of 108 cattle, 120 pigs and 104 chickens. The isolation rates of Campylobacter jejuni from cattle, pigs and chickens were 36.1%, 38.3% and 28.8%, respectively. In the biotyping of 115 strains of C. jejuni, 49.6% were belonged to biotype I, 33.9% biotype II, 10.4% biotype IV and 6.1 % biotype III. Twenty-eight strains of C. coli were 78.6% of biotype I, 21.4% biotype II. Two strains of C. laridis belonged to biotype I and II. One hundred of 105 C. jejuni cultures were typable serologically and represented 13 serogroups Serotype 4, 5, 26, 27 and 36 were encountered most frequently. Eighteen of 23 C. coli cultures were typable serologically and represented 6 serogroups. Serotype 8, 20, 21 and 31 were encountered most frequently. In the comparison of frequency of serotype between animal species, serotypes 4, 30, 5, 26 and 27 were encountered relatively common in the cattle source isolates, serotypes 26 and 36 in the pigs, and 36 and 17 in the chickens. The serotypes of C. coli encountered most frequently were serotype 8 and 31.

• 한국식품영양과학회지
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• 제31권5호
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• pp.899-904
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• 2002

알로에 및 프로폴리스 추출물과 그 혼합물의 구강 내 병원균에 대한 항균효과 및 상호작용효과를 검색하였다. 알로에 ethanol 추출물 (AE)의 구강 병원균에 대한 최소저해농도는 S. mutans, C. albicans, E. coli에 대해서는 250$\mu\textrm{g}$/mL, E. fae-calis는 270$\mu\textrm{g}$/mL로 나타났다. 프로폴리스 ethanol 추출물(PE)의 경우에는 S. mutans에 대해서는 20 $\mu\textrm{g}$/mL, E. hirae, C. albicans, E. coli에 대해서는 20$\mu\textrm{g}$/mL, E. faecalis에 대해서는 40$\mu\textrm{g}$/mL로 나타났다. 수지 및 밀납성분을 제거한 분획(PW)의 S. mutans, E. hirae, C. albicans, E. coli의 최소저해농도는 70$\mu\textrm{g}$/mL로, PE 분획보다 낮은 항균활성을 보였으며, E.faecalis의 경우에는 18$\mu\textrm{g}$/mL로 PE분획보다 높은 항균활성을 보였다. AE 및 PE의 혼합물의 항균효과를 측정한 결과, S. mutans, E. faecalis, E. hirae, C. albicans에 대하여는 상승효과 (FICI=0.375)가 있었으며, AE 및 PE의 각각의 MIC의 1/2 이하의 모든 농도범위에서 상승효과(FICI$\leq$0.5)가 있었다. 그러나 E. coli에 대하여는 AE 및 PE의 혼합에 의한 상승효과가 없었다(FICI=1.0). 또한, AE 및 PW의 혼합물의 항균효과를 측정한 결과, S. mutans, E. faecalis, E. hirae, C. albicans에 대하여는 상승효과가 적은 것 (FICI=0.75)으로 나타났다. 즉, 사용된 구강 병원균주 중에서 E. coli를 제외한 모든 균주들에 대하여 PE 및 PW는 AE의 항균효과를 강화시키는 것으로 나타났다.

• 한국미생물·생명공학회지
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• 제20권5호
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• pp.519-526
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• 1992

Bacillus pasteurii의 urease gene이 Escherichia coli HB101에서 발현된 Bacillus성 recombinant urease를 단일단백질으로 정제하고 그 효소학적 특성을, 별도로 정제한 B.pasteurii urease의 그것과 비교검토하였다. B.pasteurii urease gene이 cloning 된 E.coli HB101(pBU11)의 균체파쇄액으로 부터 TEAE-cellulose, DEAE-Sephadex A-50, Sephadex G-150, sephadex G-200 등의 이온교환 크로마토그래피와 gel filtration을 이용하여 E.coli내에서 발현된 B. pasteurii성제하였으며, 또한 B.pasteurii로부타 비활성도 185.2배의 urease를 정제하여 disc gel electrophoresis로 단일 단백으로 정제되었음을 확인하였다. 정제된 두 urease 들의 native 상태의 분자량은 공히 280,000$pm$10,000 정도로 확인되었고, SDS-electrophoresis에의 해 subunit 유무와 분자량을 확인한 결과도 67,000정도의 subunit 4개와 20,000의 subunit 1개로 된 $\alpha$$\beta$ 구조의 동일한 효소단백으로 추정할 수 있었다. Gene donor인 B. pasteurii와 cloning 된 균주 E. coli(pBU11)이 생산한 두 urease의 효소학적 특성을 비교 조사해본 결과 두 urease의 최적반응 pH는 공히 7.5로 나타났으며, pH에 대한 안정성도 두 ureaserk 공히 pH 5.5에서 10.5 사이에서 50% 이하로 활성이 떨어지지 않는 강한 pH 안정성을 보였다. 두 urese의 최적반응의 온도는 $60^{\circ}C$였으며, 비교적 온도에 대한 저항이 강한 효소임을 알았다. 두 urease의 활성에 미치는 금속이온의 영향은 $Ag^{2+}$, $Hg^{2+}$ 등에서 양효소가 모두 강한 저해현상을 받는 반면, $Mn^{2+}$, $Mg^{2+}$ 에서는 다소 촉진되는 현상을 보였다. 효소반응 저해제들의 영향을 조사해 본 결과 p-CMB, acetohydroxamic acid에 두 urease가 모두 강한 저해를 받았다. 두 urease의 $K_m$ 값과 $V_{max}$ 값은 E. coli(pBU11)의 urease는 $4.21{\times}10^{-2}mol/\ell$, $86.96\ell$mol/min 이었고, B. pasteurii urease는 $4.04{\times}10^{-2}mol/\ell$, $160\ell$mol/min이었다. 따라서 B. pasteurii의 urease나 그 urease gene으로 cloning되어 E. coliso에서 발현된 recombinant urease는 분자량이나 효소학적 특서에서 거의 동일한 효소단백임을 알 수 있었다.

• 한국환경과학회지
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• 제20권7호
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• pp.891-898
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• 2011

The aim of this research was to evaluate the effect of combination of disinfection process (electrolysis, UV process) on Escherichia coli (E. coli) disinfection and oxidants (OH radical, $ClO_2$, HOCl, $H_2O_2$ and $O_3$) generation. The effect of electrolyte type (NaCl, KCl and $Na_2SO_4$) on the E. coli disinfection and oxidants generation were evaluated. The experimental results showed that performance of E. coli disinfection of electrolysis and UV single process was similar. Combination of electrolysis and UV process enhanced the E. coli disinfection and 4-carboxybenzaldehyde (4-CBA, indicator of the generation of OH radical) degradation. It is clearly showed synergy effect on disinfection and OH radical formation. However chlorine ($ClO_2$, HOCl) and oxygen type ($H_2O_2$, $O_3$) oxidants were decreased with the combination of two process. In electrolysis + UV complex process, electro-generated $H_2O_2$ and $O_3$ were reacted with UV light of UV-C lamp and increased 4-CBA degradation(increase OH radical). Disinfection of electrolyte of chlorine type was higher than that of the sulfate type electrolyte due to the higher generation of OH radical and oxidants.

• Journal of Veterinary Science
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• 제23권3호
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• pp.37.1-37.8
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• 2022

Background: Avian pathogenic Escherichia coli (APEC) causes colibacillosis, resulting in significant economic losses in the poultry industry. Objectives: In this study, the molecular characteristics of two extended-spectrum beta-lactamase (ESBL)-producing APEC isolates were compared with previously reported ESBL-producing E. coli isolates. Methods: The molecular characteristics of E. coli isolates and the genetic environments of the ESBL genes were investigated using whole genome sequencing. Results: The two ESBL-producing APEC were classified into the phylogenetic groups C and B1 and ST410 and ST162, respectively. Moreover, the ESBL genes of the two isolates were harbored in different Inc plasmids. The EC1809182 strain, harboring the bla_CTX-M-55 gene on the plasmid, exhibited extensive homology to IncFIB (98.4%) and IncFIC(FII) (95.8%). The EC1809191 strain, harboring the bla_CTX-M-1 gene, was homologous to IncI1-I (Gamma) (99.3%). All chromosomes carried the multidrug transporter, mdf(A) gene. Mobile genetic elements, adjacent to CTX-M genes, facilitated the dissemination of genes in the two isolates, analogous to other ESBL-producing E. coli isolates. Conclusions: This study clarifies the transmission dynamics of CTX-M genes and supports strengthened surveillance to prevent the transmission of the antimicrobial-resistant genes to humans via the food chain.

• 대한의생명과학회지
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• 제18권2호
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• pp.146-151
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• 2012

Urinary tract infection (UTI) is one of the most common bacterial infections and is predominantly caused by uropathogenic Escherichia coli (UPEC). UPEC strains generally possess several genes encoding virulent factors, which are mostly adhesins, toxins, bacteriocin and siderophores. E. coli is composed of four main phylogenetic group (A, B1, B2, D) and virulent extra-intestinal strains mainly belong to groups B2 and D. Prescription of ciprofloxacin, a kind of fluoroquinolone group antibiotics, is increasing now a days, but resistance to this drug is also increasing. A total of 188 strains of E. coli were collected. Thirteen strains were collected from healthy students in 2011 and 175 strains from patients with urinary tract infection in 2010. Virulence factor genes (papC, fimG/H, sfaD/E, hlyA, cnf1, and usp) were amplified by polymerase chain reaction (PCR) methods for phylogenetic group (A, B1, B2, D) detection. Ciprofloxacin susceptibility test was performed by disk diffusion method. The identified virulence factors (VFs), phylogenetic groups and ciprofloxacin resistance in 13 E. coli strains isolated from healthy students were papC (15.4%), fimG/H (76.9%), sfaD/E (30.8%), hlyA (23.1%), cnf1 (23.1%), usp (7.7%), phylogenetic group A (23%), B1 (8%), B2 (46%), D (23%) and ciprofloxacin resistance (7.7%), while those of in 175 E. coli strains isolated from patients with UTI were papC (41.1%), fimG/H (92.5%), sfaD/E (30.3%), hlyA (10.3%), cnf1 (30.3%), usp (27.4%), phylogenetic group A (9.1%), B1 (5.1%), B2 (60.6%), D (25.1%) and ciprofloxacin resistance (29.7%). In this study, 10 out of 13 E. coli strains (76.9%) from healthy students were found to possess more than one virulence factor associated with adhesion. In addition, one E. coli strain isolated from healthy students who had never been infected with UPEC showed ciprofloxacin resistance. According to these results between the virulence factors and phylogenetic groups it was closely associated, and UPEC strains isolated from patients showed high level of ciprofloxacin resistance.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.936-942
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• 2002

When used in combination with organic acids, Pediococcus acidilactici K10 or its bacteriocin was effective in inhibiting Escherichia coli O157:H7 in vitro and in situ. P. acidilactici K10, a strain of bacteriocin-producing lactic acid bacteria (LAB), was previously isolated from kimchi in our laboratory, and the molecular weight of its bacteriocin was estimated to be around 4,500 Da by SDS-PAGE. Initially, P. acidilactici K10 and its bacteriocin could not inhibit E. coli O157:H7, when used alone. However, when they were used together with organic acids such as acetic, lactic, and succinic acids, they greatly inhibited E. coli O157:H7 in vitro. Based on these in vitro results, a real sample test with ground beef was conducted at $4^{\circ}C$ with acetic acid (0.25%) or lactic acid (0.35%) alone, and then in combination with P. acidilactici K10 (10^5 CFU/g of sample). Combined treatment of P. acidilactici K10 with lactic acid showed the most inhibitory effect: a 2.8-$log_{10}$-unit reduction of E. coli O157:H7 in ground beef during storage at $4^{\circ}C$. This result suggests that the combination of bacteriocin-producing P. acidilactici K10 and organic acids has great potential as a food biopreservative by inhibiting the growth of E. coli O157:H7.

• 대한수의학회지
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• 제50권2호
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• pp.113-116
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• 2010

To determine the prevalence of Escherichia (E.) coli O157 : H7 from pigs after the Hazard Analysis and Critical Control Point (HACCP) system has been applied to Korean swine farm since 2006, 291 fecal samples were tested between May and December in 2008. Four E. coli O157:non-H7 (1.4%) were isolated from 4 different non-HACCP-accredited farms and they didn't have virulent genes which can cause illness for human. Also, Clostridium (C.) perfringens, Salmonella spp. and E. coli enterotoxins were tested using multiplex PCR. The positive rate for these pathogens of non-HACCP-accredited farms was higher than that of HACCP-accredited farms, and especially in case of C. perfringens, E. coli enterotoxins LT and STa, it was statistically significant (p < 0.05). Thus, the early implementation of the HACCP program is expected to greatly contribute to the safety of livestock products as well as food hygiene.

• 한국미생물·생명공학회지
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• 제15권6호
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• pp.441-445
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• 1987

알카리성 amylase를 내는 Bacillus sp. AL-8의 알카리성 amylase 유전자를 amylase를 생성하지 않는 Escherichia coli HB101에 pBR322를 vector로 하여 형질전환하였다. E. coli도 알카리성 amylase를 생성하여 5$0^{\circ}C$에서 최적 활성온도를 가지며 5$0^{\circ}C$까지 열안정성을 갖고, pH10에서 최적 활성 pH를 나타내는 동시에 pH8-10에서 안정하였다. 알카리성 amylase 유전자가 E. coli에 형질전환되어 donor 세포와 같은 효소 성질을 갖고 있으며 pBR322로 삽입된 유전자는 pJW8에서 5.8kb이며 pJW200에서는 3.0kb로 E. coli에서 안정하게 발현되었다.

• 대한수의학회지
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• 제60권3호
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• pp.173-177
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• 2020

Edible offal is easily contaminated by Escherichia coli (E. coli) and fluoroquinolone (FQ)-resistant E. coli is considered a serious public health problem, thus, this study investigated the genetic characteristics of FQ-resistant E. coli from edible offal. A total of 22 FQ-resistant E. coli isolates were tested. A double mutation in each gyrA and parC led the highest MIC. Four (18.2%) isolates carried plasmid-mediated quinolone resistance genes. The fimH, eaeA, escV, astA, and iucC genes were confirmed. Seventeen isolates (77.3%) were positive for plasmid replicons. The isolates showed high genetic heterogeneity based on pulsed-field gel electrophoresis patterns.