• The Korean Journal of Food And Nutrition
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• v.14 no.6
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• pp.579-584
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• 2001

Chitooligosaccharides were prepared by enzymatic hydrolyzing of crab shell chitosan. Low Molecular Meight chitooligosaccharides(LMW-chitooligosaccharides) , 64.3% of which was composed of trimer, tetramer, and pentamer, was obtained by hydrolyzing chitosan with the chitosanase originated Bacillus pumilus BN -262. High Molecular Meight chitooligosaccharides ( HMW-chitooligosaccharides ) , 49.3% of which was composed of chitooligosaccharides over heptamer, was obtained by hydrolyzing chitosan with the cellulase originated Trichoderma viride. Antimicrobial activity and colony forming inhibitory activity of chitooligosaccharides were tested. MIC of LMW-chitooligosaccharides against Bacillus cereus, Bacillus subtilis, Candida albicans, Escherichia coli, Escherichia coli O157 : H7, Lactobacillus plantarum, Listeria monocytogenes, Pseudomonas aeruginosa, Salmonella enteritidis, Salmonella typhimurium, Staphylococcus aureus and Streptococcus mutans was 1.5%, 1.5% above 2.0%, 1.5%, 1.5%, below 0.5%, 2.0%, 1.5%, above 2.0%, 1.0%, 1.5% and 1.0% respectively. .

• KSBB Journal
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• v.10 no.3
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• pp.249-256
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• 1995

${\gamma}$-Glutamylcysteine production by the immobilized microbial system of recombinant Escherichia coli and yeast was investigated. ${\gamma}$-Glutamylcysteine was synthesized from L-glutamic acid and L-cysteine in the presence of ATP by the reaction catalyzed by ${\gamma}$-glutamylcysteine synthetase. An immobilized microbial cell system was developed for the efficient ${\gamma}$-glutamylcysteine production. Recombinant Escherichia coli and yeast were immobilized by alginate. Production of ${\gamma}$-glutamylcysteine was better with the recombinant Escherichia coli for both the synthesis of ${\gamma}$-glutamylcysteine and the ATP regeneration than the mixed system of recombinant Escherichia coli and yeast. The proper radio of recombinant Escherichia coli to yeast was experimentary observed to be 1:4 in the mixed system. Although the immobi1ized system had the slower reaction rate, its reaction stability was increased by 10%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.4
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• pp.322-328
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• 2009

Three-hundred and sixteen Escherichia coli strains from seawater, and a variety of farmed fishes, including oliver flounder (Paralichthys olivaceus), black rock fish (Sebastes schlegeli), red sea bream (Pagrus major) and sea bass (Lateolabrax japonicus) between May to October in 2004, were tested by agar dilution method to determine their susceptibility patterns to 17 antimicrobial agents. Overall, 92.1% of Escherichia coli isolates from samples showed antimicrobial resistance to at least one antimicrobial agent and the multiple resistance was seen in 173 isolates (54.7%). The resistance of E. coli isolates to tetracycline (74.1%) was highest, followed by cephalothin (69.9%), doxycycline (66.5%), streptomycin (47.2%), ampicillin (46.2%), cefazolin (31.6%), enrofloxacin (31.0%). norfloxacin (28.2%). The most frequent resistance pattern was TE-D-CF-CIP-ENO-NOR-AM-S-C-SXT-AmC-CZ (14.7%), followed by CF (6.2%), TE (5.1%), TE-CF (4.5%) in 177 isolates from fishes and TE-D-CF (7.2%) followed by TE-D-CF-S (5.8%), CF and TE-D-S (3.6%) in 139 isolates from seawater.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.10
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• pp.1265-1269
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• 2017

This study was performed to evaluate the effects of combined treatment of clove bud essential oil (CBEO) and mild heat (MH) on inactivation of Escherichia coli O157:H7 inoculated onto red oak leaves. Combined treatment of 0.2% CBEO with MH at $50^{\circ}C$ exhibited the highest inhibitory effect against E. coli O157:H7 among treatments, resulting in 1.45 log reduction compared with water washing treatment. In addition, inhibitory effect of the combined treatment was maintained during storage of red oak leaves at $4^{\circ}C$ for 9 days, showing 1.67~2.25 log reductions compared with non-treated samples. Thus, these results indicate that combined treatment with CBEO/MH can be used to ensure the microbiological safety of fresh leaf vegetables such as red oak leaves during storage.

• Korean Journal of Microbiology
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• v.28 no.2
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• pp.169-173
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• 1990

For the overproduction of L-phenylalanine using Escherichia coli, the authors constructed various recombinant plasmids including pMW 10, pMW 11 and pMW 12. The $aroF{FR}$ and $pheA^{FR}$ genes for the production of L-phenylalanine were isolated from Escherichia coli MWEC 101-5 strains. The productivity and atability of Escherichia coli regulatory mutants containing recombinant plasmids were investigated to evaluate the efficiency of the $aroF^{FR}$ and $pheA^{FR}$ genes. The MWEC 101-5/pMW 11 strain produced 24.3g/l of L-phenylalanine while its stability was 73.8 percent. The specific activity of prephenate dehydratase in the MWEC 101-5/pMW 11 strain increased by 26-fold compared with that of Escherichia coli K-12.

• Childhood Kidney Diseases
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• v.10 no.2
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• pp.192-200
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• 2006

Purpose : This study was performed to identify longitudinal changes in the prevalence of organisms isolated from urinary tract infection(UTI) and in the pattern of Escherichia coli susceptibility to antibiotics during the past 10 years in children with UTI. Methods : We performed a retrospective study of a total of 192 urine cultures from children with UTI in the Department of Pediatrics, Seoul Adventist Hospital over two periods(1st: 1995-2000, 2nd:2001-2005). Antimicrobial susceptibility of the isolates was compared between the two groups. Results : The pathogens of UTI in the two groups were similar. In the first period, E. coli was the leading uropathogen(66.2%) followed by Klebsiella pneumoniae(7.8%), Enterobacter cloacae(6.5%), and others(19.5%). In the second period, E. coli was the leading uropathogen(67%) followed by K. pneumoniae(12.2%), E. cloacae(3.5%), Enterobacter aerogenes(3.5%), and others(13.8%). The susceptibility pattern of E. coli to amoxicillin/clavulanate(87.5%, 81.0%) did not present any statistically significant difference between the two periods(P>0.05). The susceptibility of E. coli to TMP/SMX(52.4%, 50.0%) was still low with no significant difference between the two periods(P>0.05). Conclusion : Our results suggest that the use of amoxicillin/clavulanate is still an excellent therapeutic option in children with UTI. The low rate of susceptibility to TMP/SMX against uropathogens suggest that TMP/SMX may be reevaluated as the first-line therapeutic drug for UTI.

• Microbiology and Biotechnology Letters
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• v.18 no.3
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• pp.268-272
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• 1990

The structural gene (zadhII) encoding an alcohol dehydrogenase II from Zyrnornonas mobilis was cloned into Escherichia coli in our laboratory (Yoon et al., 1989. Kor. J. Microbiol. Biotechnol.). From E. coli (pADS93) carrying the zadhII gene, the Z mobilis alcochol dehydrogenase II (ZADH-II) was purified by sonication, $(NH_4)_2SO_4$, fractionation, and chromatography. The ZADH-I1 enzyme produced by Z. mobilis cell was also purified to compare to the enzyme produced by E. coli (pADS93). The purified enzyme from cell extract of E. coli (pADS93) was identified to be a tetramer being composed of four identical subunits having molecular weight of 40, 000 dalton like that of Z. mobilis. The pH optimum for the reaction oxidizing ethanol to acetaldehyde was 10.0 while the optimum for the reverse reaction was 7.5-8.5. The apparent $K_m$ values for ethanol and NAD + were $1.2 \times 10^{-1}M$and $5.1\times 10^{-5}M$, respectively. In addition, it was found that the $K_m$ value for acetaldehyde was very lower than that for ethanol.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.6
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• pp.800-806
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• 2016

In total, 151 Escherichia coli isolates from Ruditapes philippinarum in Gomso Bay were analyzed for their susceptibility to 18 different antimicrobial agents and for genes associated with virulence. For virulence genes, each strain of the isolates was positive for the enterotoxigenic E. coli (ETEC)-specific heat-stable toxin (estA), enteroinvasive E. coli (EIEC)-specific invasion-associated locus (iaa) gene and enteropathogenic E. coli (EPEC)-specific attaching and effacing (eae) gene. According to a disk diffusion susceptibility test, resistance to ampicillin was most prevalent (23.2%), followed by resistance to amoxicillin (22.5%), ticarcillin (20.5%), tetracycline (18.5%), nalidixic acid (12.6%), ciprofloxacin (10.6%), streptomycin (9.9%), and chloramphenicol (6.6%). More than 35.8% of the isolates were resistant to at least one antimicrobial agent, and 19.9% were resistant to four or more classes of antimicrobials; these were consequently defined as multidrug resistant. Minimum inhibitory concentration (MIC) ranges for the antimicrobial resistance of the 15 different antimicrobial agents of 54 E. coli strains were confirmed by varying the concentrations from $32-2,048{\mu}g/mL$. Overall, these results not only provide novel insights into the necessity for seawater and R. philippinarum sanitation in Gomso Bay but they also help to reduce the risk of contamination by antimicrobial-resistant bacteria.

• Food Engineering Progress
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• v.14 no.3
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• pp.202-207
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• 2010

Low-pressure plasmas (LPPs) were generated with different gases such as air, oxygen and nitrogen, and their inactivation effects against Escherichia coli were compared in order to evaluate the potential as a non-thermal microbial disinfection technology. Homogeneous plasmas were generated under low pressure below 1 Torr at gas flow rate of 350 mL/min regardless the types of gases. Temperature increases by LPPs were not detrimental showing less than ${10^{\circ}C}$ and ${25^{\circ}C}$ increases after 5 and 10 min treatments, respectively. The smallest temperature increase was observed with air LPP, and followed by oxygen and nitrogen LPPs. More than 5 log reduction in E. coli was achieved by 5 min LPP treatment but the destruction effect was retarded afterward. The LPP inactivation was represented by a iphasic first order reaction kinetics. The highest inactivation rate constant was achieved in air LPP and followed by oxygen and nitrogen LPPs. The small D-values of the LPP also supported its potentialities as a non-thermal food surface disinfection technology in addition to the substantial microbial reduction of more than 5 logs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.6
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• pp.673-681
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• 2018

We isolated and characterized Escherichia coli (E. coli) from oyster Crassostrea gigas and inland pollution sources on Yongnam-Gwangdo island and neighboring areas on the southern coast of Korea in 2014-2015. A total of 222 strains of E. coli were isolated from 132 oysters and 88 samples from inland pollution sources. These 222 isolates were tested for their susceptibility to 24 antimicrobial agents, and 221 isolates were found resistant to the tested antibiotics. Of these 99.5% and 70.7% of the isolates showed very high resistance to rifampin and cephalothin respectively, followed by tobramycin (23.4%), streptomycin (20.2%), tetracycline (19.4%), cefepime (18.9%), ceftazidime (18.9%) and nalidixic acid (16.7%). The resistance rate of E. coli isolated from oysters was higher than that from inland pollution sources. In addition, multiple resistance to at least four antibiotics were present in 73.2% and 26.5% of E. coli isolates from oysters and inland pollution source samples, respectively.