• Journal of Environmental Health Sciences
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• v.33 no.5
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• pp.403-407
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• 2007

The inhibitory effect of the food processing agent on growth of Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes was performed with organic acid, and combination of citric acid, acetic acid, propionic acid and vanillic acid. The minimun inhibitory concentration(MIC) of propionic acid was 5,000 ppm in E. coli O157:H7, 2,500 ppm in Salmonella Enteritidis and Listeria monocytogenes. MIC of citric acid was 10,000 ppm in E. coli O157:H7 and Salmonella Enteritidis, 2,500 ppm in Listeria monocytogenes. MIC of acetic acid was 2,500ppm, while in vanillic acid was 5,000 ppm in Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes. MIC of combined organc acid in E. coli O157:H7 were 2,500ppm in PC, 1,250 ppm in PA, PV, CA, CV and AV. MIC of combined organc acid in Salmonella Enteritidis were 2,500 ppm in PC, PA, PV, CA, and CV, 1,250 ppm in AV. MIC of combined organc acid in Listeria monocytogenes were 1,250 ppm in all treatment group. MIC of combined treatment of three organc acid in E. coli O157:H7, S. Enteritidis and L. monocytogenes were 1,250 ppm in PCA, PCV, PAV and CAV. The inhibitory effect of organc acid in E. coli O157:H7, S. Enteritidis and L. monocytogenes could be confirmed from the result of this experiment. Therefore, it was expected that the food process would increase or maintain by using organic acid.

• Journal of Food Hygiene and Safety
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• v.12 no.3
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• pp.175-180
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• 1997

Escherichia coli O157:H7 and Salmonella ser. typhimurium are pathogens involved in food poisoning in numerous countries. This study aimed to obtain knowleges on the survival of E. coli O157:H7 KSC 109 and S. ser. typhimurium ATCC 14028 in fermentedmilk products which were on sale in Suwon Yakult supplier. To the final concentration of 103~104 cfu/$m\ell$ of E. coli O157:H7 KSC 109 or S. wer. typhimurium ATCC 14028 in the fermented milks, Metchnikoff, Ace, Yakult, Mastoni and Super 100 were inoculated with these pathogens and then were stored at 4$^{\circ}C$ and viable cells of these pathogens were periodically counted. The results showed that the survival of two pathogens differed in the different types of fermented milks tested. Number of suriviving E. coli O157:H7 KSC 109 and S. ser. typimurium ATCC 14028 cells (initial inoculum, 103~104 cfu/$m\ell$) were decreased to 101, 102 cfu/$m\ell$ in Ace after 100 hours, and were decreased gradually to 101 cfu/$m\ell$ in Yakult after 250 hours. In the other fermented milks, viable cells of E. coli O157:H7 KSC 109 was not drastically decreased but those of S. ser. typhimurium ATCC 14028 was decreased gradually to 102 (Mastoni), and to 101 cfu/$m\ell$ (Super 100) after 250 hours. It appeared that S. ser. typhimurium ATCC 14028 was more susceptible than E. coli O157:H7 KSC 109 at low pH. Vibale cells of E. coli O157:H7 KSC 109 was not drastically decreased in most of fermented milks tested except Ace and Yakult, but in general, S. ser. typhimurium ATCC 14028 was drastically decreased in most of the fermented milks. The major ingibition factor against these pathogens in the fermented milks during storage at 4$^{\circ}C$ appeared to be the acidity and the metabolites produced by the starters bacteria used in fermented milk products.

• Microbiology and Biotechnology Letters
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• v.15 no.5
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• pp.346-351
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• 1987

A cellulase gene of Clostridium themocellum was transferred to Escherichia coli by molecular cloning with pBR322. The gene was carried in a Hind III digested DNA sequence of about 1.8 kb. This Rind III fragment expressed activities on carboxymethyl cellulose (CMC) and on filter gaper in E. coli. The expression of clostridial cellulase gene in E. coli was studied and compared with the pro-ducts of cellulase genes in C. themocellum.

• Fisheries and Aquatic Sciences
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• v.6 no.1
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• pp.20-26
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• 2003

A bacterial strain was isolated from seawater to screen for phytase activities. A colony had the highest activity and was identified as an Escherichia coli strain. Using primers derived from E. coli acid phosphatase appA sequence, we cloned a 1,495 bp DNA fragment connected with the pGEM-T vector. It was over-expressed under lac promoter combined with its native promoter in E. coli $DH5\alpha$. The expression of the phytase gene occurred during late exponential growth and the intracellular phytase production was 16.9 units/ml. The yield of recombinant phytate was 412-fold higher than that of wild type E. coli K13.

• Korean Journal of Veterinary Research
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• v.17 no.1
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• pp.5-8
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• 1977

One hundred and fifty seven Escherichia coli strains isolated from 18 cattle (9 dairy cattle received penicillin, streptomycin (SM) or sulfadimethoxine for treatment of diseases and 9 Korean native cattle not received antibiotics) were studied for the drug resistance and distribution of R factors. Of 88 E. coli strains isolated from cattle not received antibiotics, only 1 strain was resistant to SM, but about 46 per cent of 69 E. coli strains isolated from cattle received antibiotics were resistant to SM, tetracycline (TC), ampicillin (AP), kanamycin (KM), chloramphenicol (CM), and sulfisomidine (Su), alone or in combination thereof. Of resistant strains, about 72% were resistant to three or more antibiotics, but 28% were found to singly resistant. The most frequent resistant pattern was triple resistance to AP, KM and Su (37.6%), and quadruple one to SM, TC, CM and Su (12.5%). About 28% of resistant strains carried R factors which were transferable to E. coli ML 1410 $NA^r$ by conjugation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.280-285
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• 1995

To develop natural food preservatives, antimicrobial effect of the ethanol extract of leaf mustard against E. coli and S. aureus were examined in terms of compositions and leakage of cellular materials in the microorganisms treated with the extract. No effect of the concentration of ethanol extract on the fatty acid composition of E. coli and S. aureus at logarithmic phase was showen, but the content of palmitic and palmitoleic acid of E. coli slightly increased and decreased, respectively, and the content of palmitic and margaric acid of S. aureus slightly increased, when compared to each control. Ethanol extract did not affect most of the amino acids E. coli and S. aureus at logarithmic phase ; however, some of them(proline, glycine, valine and histidine of E. coli and proline, methionine and histidine of s. aureus) were elevated and some other amino acid(aspartic acid, glutamic acid, tyrosine and arginine of E. coli and aspartic acid, glutamic acid, glycine, alanine and lysine of Staph. aureus) found to be decreased. The amount of cell body protein leaked from E. coli and S. aureus increased to 1.02 and 0.22mg/g cell weight, respectively, as compared to controls. Similarly, the substances with absorbance at 260 nm from E. coli and s. aureus increased to 0.12 and 0.06mg/g cell weight, respectively.

• Korean Journal of Veterinary Research
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• v.55 no.3
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• pp.191-197
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• 2015

Escherichia (E.) coli is commensal bacteria found in the intestine; however, some pathogenic strains cause diseases in animals and humans. Although E. coli does not typically produce hydrogen sulfide ($H_2S$), $H_2S$-producing strains of E. coli have been identified worldwide. The relationship between virulence and $H_2S$ production has not yet been determined. Therefore, characteristics of $H_2S$-producing isolates obtained from swine feces were evaluated including antibiotic resistance patterns, virulence gene expression, and genetic relatedness. Rates of antibiotic resistance of the $H_2S$-producing E. coli varied according to antibiotic. Only the EAST1 gene was detected as a virulence gene in five $H_2S$-producing E. coli strains. Genes conferring $H_2S$ production were not transmissible although the sseA gene encoding 3-mercaptopyruvate sulfurtransferase was detected in all $H_2S$-producing E. coli strains. Sequences of the sseA gene motif CGSVTA around Cys238 were also identical in all $H_2S$- producing E. coli strains. Diverse genetic relatedness among the isolates was observed by pulsed-field gel electrophoresis analysis. These results suggested that $H_2S$-producing E. coli strains were not derived from a specific clone and $H_2S$ production in E. coli is not associated with virulence genes.

• Microbiology and Biotechnology Letters
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• v.27 no.5
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• pp.419-425
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• 1999

Prophylactic effects of Bifidobacterium longum HY8001, Korean isolate, against Escherichia coli O157:H7 and Salmonella typhimurium DT104 enteric infection were examined at four groups of specific pathogen free(SPF)-ICR mouse for each pathogen. B. longum HY8001+B. typhimurium DT104+B. longum HY8001(BL+ST+BL) group and B. longum HY8001+E. coli O157:H7+B. longum HY8001(BL+E+BL) group were fed with B. longum HY8001 before and after E. coli O157:H7 or s. typhimurium DT104 challenge, while B. longum HY8001+S. typhimurium DT104(BL+ST) and B. longum HY8001+e. coli O157:H7(BL+E) groups were fed with B. longum HY8001 only before E. coli O157:H7 or S. typhimurium DT104 challenge. E. coli O157:H7(E) and S. typhimurium DT104(ST) groups were challenged with each pathogen without B. longum HY8001 administration and control groups were administered with phosphate buffered solution(PBS). After the oral administration with B. longum HY8001(109cfu), th emice were challenged with E. coli O157:H7(2$\times$1010cfu) or S. typhimurium DT104(108cfu) and the mortality rate and the fecal shedding of challenged pathogen were also examined define the reactivity of the B. longum HY8001. Production of toxin neutralizing substance(s) of B. longum HY8001 was determined by cell cytotoxicity assay using Vero cells. Fecal shedding of th eS. typhimurium DT104 was significantly decreased in BL+ST+BL group fed with B. longum HY8--1 before and after challenge(p<0.05), while the fecal shedding s of S. typhimurium DT104 in BL+ST and St groups remained more than 106cfu. the protective effect of the B. longum HY8001 against E. coli O157:H7 was significantly high only in BL+E+BL group fed with b. longum Hy8001 before and after E. coli O157:H7 challenge from the result of fecal E. coli O157:H7 isolation rate, mortality rate, and intestinal contents culture to detect E. coli O157:H7. the mortality rate of the BL+e and E groups. The cytopathic effect (CPE) of the Vero cytotoxin (Shiga like toxin I & II) in Vero cell was neutralized in B. longum HY8001 culture supernatant added wells which indicate the presence of soluble Vero cytotxin neutralizing substance(s) in B. longum HY8001 culture suprnatant.

• Korean Journal of Veterinary Research
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• v.28 no.1
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• pp.59-65
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• 1988

This paper deals with the 0 groups of citrate utilizing variants of Escherichia coli ($Cit^+$ E. coli) isolated from cattle, the production of colicin, hemolysin, K99 antigen, heat stable enterotoxin, and the isolation of plasmid DNA. Among 42 $Cit^+$ E. coli, 12 strains were 020, 9 strains 08, 5 strains 045, 3 strains 0115, 1 strain 064, 1 strain 0139 and remaining strains(11) were untypable. Thirty-nine(81.3%) out of 48 $Cit^+$ E. coli were produced colicin and 13(27.0%) were produced hemolysin. Of 12 $Cit^+$ E. coli bearing K99 antigen, 6(50.0%) were produced heat stable enterotoxin. In gel electrophoresis for the isolation of plasmid DNA, the number of plasmids varied from 1 to 7 in 10 $Cit^+$ E. coli. It's molecular weight ranged from 2 to 50 Mdalton, and 50 Mdalton plasmid was commonly existed in all strains.

• Microbiology and Biotechnology Letters
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• v.32 no.3
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• pp.212-217
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• 2004

The gene coding for mannanase from Bacillus subtilis WL-7, a number of glycosyl hydrolase family 26, was hyperexpressed in Escherichia coli. Two recombinant plasmids, pE7MAN and pENS7, were constructed by introducing the complete mannanase gene and the mature mannanase gene lacking N-terminal signal peptide region into a expression vector pET24a(＋), respectively. The level of mannanase produced by E. coli BL21 (DE3) carrying pENS7, which included the mature mannanase gene, was considerably higher than that by E. coli BL21 (DE3)/pE7MAN. Almost mannanase produced by the recombinant E. coli carrying pENS7 at growth temperature of $37^{\circ}C$ existed as inactive enzyme of insoluble form. Growth at temperature below $31^{\circ}C$ increased the soluble fraction of mannanase having catalytic activity in the recombinant E. coli cells. The highest productivity of active mannanase was observed in cell-free extract of the recombinant E. coli grown at growth temperature ranging from $25^{\circ}C$ to $28^{\circ}C$, while mannanase activity per soluble protein of the cell-free extract was highest in the cells grown at $^31{\circ}C$.