• Korean Journal of Veterinary Research
• /
• v.31 no.1
• /
• pp.55-61
• /
• 1991

The correlation between in vitro Congo-red binding properties of E coli and in vivo invasiveness of the organisms in SPF chickens and mice was investigated. Congo-red positive E coli colonies were dark-red color with a typical colonial morphology of rough appearance when grown on Congo-red medium, while Congo-red negative colonies showed pale-pink color and smooth surfaced colonial morphology. Pathogenicity of 10 Congo-red positive E coli for mice was observed in 92.5% but that of 5 Congo-red negative E coli was 45%. Invasiveness of 10 Congo-red positive E coli for chickens was observed in 96% of the SPF chickens tested but that of 5 Congo-red negative E coli was 16% only. These results of pathogenicity studies with E coli isolates indicate a significant correlation between Congo-red binding ability and virulence in avian Escherichia coli.

• Microbiology and Biotechnology Letters
• /
• v.16 no.2
• /
• pp.111-118
• /
• 1988

The growth inhibition of enteropathogenic Escheriohia coli $A_2$and Escherichia coli G$_7$, causing the diarrhea in piglets, by the organic acid producing bacteria was studied in vitro. The metabolites of the organic acid bacteria, such as lactic acid, acetic acid inhibited the growth of E. coli $A_2$and E. coli G$_7$ in BL medium. The more the organic acid producing bacteria have ability to produce the organic acids, the higher these bacteria excelled the inhibitory efficacy against enteropathogenic E. coli. Among the strains examined, Lactobacillus casei Y and Streptococcus faecium C showed relatively strong growth inhibition against enteropathogenic E. coli.. When the organic acid producing bacteria and the enteropathogenic E. coli were incubated simultaneously in BL medium, bacteriostasis of E. coli was observed when the pH of BL culture was lowered to 5.0, and bacteriocidal effect was observed when the pH became Bess than 4.5, E. coli. $A_2$was more resistant to the organic acid bacteria than E. coli G$_7$.

• Microbiology and Biotechnology Letters
• /
• v.14 no.2
• /
• pp.161-168
• /
• 1986

A 1.95Kb Sau3Al fragment coding for $\alpha$-amylase from Bacillus amyloliquefaciens was isolated by the shotgun method using Escherichia coli as a host. The genome of Bacillus amyloliquefaciens was partially digested with the restriction endonuclease Sau3Al and joined to plasmid YRp7 cleaved with the restriction endonuclease BamHI. The $\alpha$-amylase gene present in a 1.95Kb insert was stably maintained and expressed in Escherichia coli. The amount of $\alpha$-amylase activity produced by Escherichia coli containing the hybrid plasmid pEA24 was about 65% of the activity produced by the donor Bacillus amyloliquefaciens strain. The properties of $\alpha$-amylase produced by Escherichia coli were very similar to those produced by Bacillus amyloliquefaciens as based on optimum temperature, pH, and effect of CaCl$_2$ concentration. About 70% of the $\alpha$-amylase produced by Escherichia coli was localized in the periplasmic space, whereas the remaining enzyme was localized in the inner part of the cell.

• Parasites, Hosts and Diseases
• /
• v.49 no.4
• /
• pp.349-356
• /
• 2011

The existence of symbiotic relationships between Acanthamoeba and a variety of bacteria is well-documented. However, the ability of Acanthamoeba interacting with host bacterial pathogens has gained particular attention. Here, to understand the interactions of Escherichia coli K1 and E. coli K5 strains with Acanthamoeba castellanii trophozoites and cysts, association assay, invasion assay, survival assay, and the measurement of bacterial numbers from cysts were performed, and nonpathogenic E. coli K12 was also applied. The association ratio of E. coli K1 with A. castellanii was 4.3 cfu per amoeba for 1 hr but E. coli K5 with A. castellanii was 1 cfu per amoeba for 1 hr. By invasion and survival assays, E. coli K5 was recovered less than E. coli K1 but still alive inside A. castellanii. E. coli K1 and K5 survived and multiplied intracellularly in A. castellanii. The survival assay was performed under a favourable condition for 22 hr and 43 hr with the encystment of A. castellanii. Under the favourable condition for the transformation of trophozoites into cysts, E. coli K5 multiplied significantly. Moreover, the pathogenic potential of E. coli K1 from A. castellanii cysts exhibited no changes as compared with E. coli K1 from A. castellanii trophozoites. E. coli K5 was multiplied in A. castellanii trophozoites and survived in A. castellanii cysts. Therefore, this study suggests that E. coli K5 can use A. castellanii as a reservoir host or a vector for the bacterial transmission.

• Journal of Food Hygiene and Safety
• /
• v.12 no.1
• /
• pp.78-82
• /
• 1997

Surface swab samples from beef (188), pork (240) and chicken (95) carcasses were collected from slaughterhouse in Kangwon and Kyunggi areas from March through July 1996. The samples were examined on the level of E. coli biotype I relevant to fecal contamination due to unsanitary processing control and the existence of verocytotoxin-producing E. coli (VTEC). E. coli biotype I were confirmed from 38.8% of beef, 40.0% of pork, and 69.5% of chicken carcasses. Little variation was noted among three sampling points; rump, flank and neck of beef, ham, belly and jowls of pork. coli O157:H7 was only confirmed from 2 of 188 beef carcasses. E. coli biotype I. All the isolated E. coli O157 showed positive for vero cell cytotoxicity test. Isolation rate of E. coli O157 in summer was higher than in spring. In case of pork and chicken carcasses, E. coli O157 was isolated in summer only.

• Food Science of Animal Resources
• /
• v.40 no.4
• /
• pp.668-674
• /
• 2020

Manuka honey (MH) has been shown anti-bacterial activity against several pathogenic bacteria. However, the inhibitory effect of MH on biofilm formation by Escherichia coli O157:H7 has not yet been examined. In this study, MH significantly reduced E. coli O157:H7 biofilm. Moreover, pre- and post-treatment with MH also significantly reduced E. coli O157:H7 biofilm. Cellular metabolic activities exhibited that the viability of E. coli O157:H7 biofilm cells was reduced in the presence of MH. Further, colony forming unit of MH-treated E. coli O157:H7 biofilm was significantly reduced by over 70%. Collectively, this study suggests the potential of anti-biofilm properties of MH which could be applied to control E. coli O157:H7.

• Archives of Pharmacal Research
• /
• v.19 no.5
• /
• pp.353-358
• /
• 1996

E. coli 11 and E. coli 101, clinical isolates of Escherichia coli were resistant to various quinolones, especially MICs to norfloxacin of both strains were higher than 100 mg/ml. In the presence of carbonyl cyanide m-chlorophenylhydrazone, a proton gradient uncoupler, norfloxacin uptake in both strains was increased, suggesting that an efflux system play an important role in the norfloxacin resistance. Outer membrane proteins of the susceptible and resistant strains which could affect the route of norfloxacin entry into cells were different. When quinolone resistance determining region(QRDR) of gyrA was amplified using PCR and cut with Hinf I, QRDR in the susceptible strain yielded two fragments while QRDRs in E. coli 11 and E. coli 101 yielded only one uncut fragment. When DNA sequence of QRDR was analyzed, there were two mutations as Ser-83 and Asp-87 in both resistant strains. these residues were changed to Leu-83 and Asn-87, respectively. These results showed that the norfloxacin resistance of E. coli 11 and E. coli 101 was resulted from multiple changes-an altered DNA gyrase A subunit, a change in route of drug entry, and reduction in quinolone concentration inside cells due to an efflux system.

• Journal of Life Science
• /
• v.16 no.3 s.76
• /
• pp.415-419
• /
• 2006

The epoxide hydrolase (EH) of Rhodotorula glutinis which has a high enantioselectivity against aromatic epoxide substrates was expressed to high levels in Escherichia coli based on codon usage. We analysed the Preference of codon usage between the yeast, R. glutinis, and bacteria, E. coli. E. coli, Rosetta(DE3)pLysS, harbors pRARE plasmid with tRNA genes for rare-codons was employed as a host strain. The recombinant E. coli expressing R. glutinis EH showed an enhanced enantioselective hydrolysis activity toward racemic styrene oxide. Enantiopure (S)-styrene oxide with a high enantiopurity of 99% ee (enantiomeric excess) was obtained from racemic substrates.

• Food Science of Animal Resources
• /
• v.37 no.6
• /
• pp.799-803
• /
• 2017

In the present study, centrifugation and filtration pretreatments were evaluated to decrease sample preparation time and to improve the sensitivity and specificity of multiplex polymerase chain reaction (PCR) for the detection of low levels of pathogenic Escherichia coli in various foods. Pathogenic E. coli (E. coli NCCP11142, E. coli NCCP14037, E. coli NCCP 14038, E. coli NCCP14039, and E. coli NCCP15661) was inoculated into pork, beef, and baby leafy vegetables at 1, 2, and 3 Log CFU/g. The samples were shaken 30 times (control), then centrifuged or filtered. DNA extracts from the samples were subjected to PCR using the $Powerchek^{TM}$ Diarrheal E. coli 8-plex Detection Kit. In the pork samples, no E. coli was detected in the control samples, while E. coli were detected in 100% of 3-Log CFU/g inoculated and centrifuged samples, and in 100% of 2 and 3-Log CFU/g inoculated, and filtered samples. In the beef samples, all control samples appeared to be E. coli-negative, while E. coli was detected in 50-75% of centrifuged samples, regardless of inoculated level, and in 100% of 2 and 3-Log CFU/g inoculated, and filtered samples. In baby leafy vegetables, E. coli were not detected in 25-50% of the control samples, while E. coli were detected in 0-25% of the centrifuged samples, and 75-100% of the filtered samples, depending on the inoculum amount. In conclusion, filtration pretreatment can be used to minimize sample preparation time, and improve the sensitivity and specificity of rapid detection of pathogenic E. coli in various foods.

• The Korean Journal of Ecology
• /
• v.25 no.5
• /
• pp.353-358
• /
• 2002

We examined the effect of 12 main monoterpenes in Pinus plants on growth inhibition of Escherichia coli and Aspergillus nidulans. We tested four concentrations of each compound by comparing the clear zone with controls. (R)-(-)carvone, (S)(+)carvone, (1R)(-)fenchone, (-)menthone, α-pinene, (1S) (-)verbenone and (+)β - pinene had a inhibition effect on E. coli. (R)-(-)carvone, (S)(+)carvone, (+) β-pinene, geranyl-acetate, α-pinene, and (1S)(-)verbenone had inhibitory effects on the growth of A. nidulans. Geranyl-acetate inhibit growth of A. nidulans, however not to E. coli. And (1R)(-)fenchone and (-)menthone inhibit growth of E. coli, but not to A. nidulans. Myrcene, sabinene, bornyl acetate, and limonene had no inhibitory effects on E. coli and A. nidulans, eventhough at the highest concentration. All these results suggested that some selected monoterpenes had antifungal activities depend on the species of microorganism.