• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1976.10a
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• pp.188.2-188
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• 1976

E. coli B 및 E. coli K-12의 Ion 변리주는 저중의 UV 조사에 의해 확산 및 단백질 합성은 그대로 지속되나 세포분열능은 상실되어 격막이 없는 다핵의 filament를 형성하므로 한무배지상에서 colony가 형성되지 않는다. 이와같은 균에 동일균 또는 타의 균체추출액을 가하어 주므로써 세포분열은 재개되며 그 활성물질중 $\beta-NAD가$ 중요한 인자로 작용함은 이미 발표되었으며 본보에서는 NAD 이외의 고분자활성물질에 대해 보고코저 한다.(중략)

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.8
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• pp.1195-1199
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• 2011

Inactivation of foodborne pathogenic bacteria in corn silk tea was evaluated using a microwave plasma sterilization system (MPSS). Corn silk tea was inoculated with Escherichia coli and Listeria monocytogenes, treated with an MPSS treatment, and stored at 25$^{\circ}C$ for 12 days. The one, two, and three cycles of treatment with MPSS reduced the population of E. coli by 1.14, 2.49, and 5.72 log CFU/mL, respectively, compared to that of the control. In the case of L. monocytogenes, one, two, and three cycles of MPSS treatment reduced the population by 1.93, 4.49, and 6.62 log CFU/mL, respectively. Both E. coli and L. monocytogenes were eliminated within four cycles of treatment with MPSS, and even after 12 days of storage, the bacteria were not detected. Total polyphenol content in the corn silk tea did not change much among treatments, and turbidity of the corn silk tea improved following four cycles of MPSS treatment. These results suggest that MPSS treatment can be useful for improving the microbial safety and quality of corn silk tea during storage.

• Korean Journal of Microbiology
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• v.20 no.1
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• pp.11-20
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• 1982

A study was undertaken to examine the effect of curing agents on the stability, curing and segregation of R plasmid pSL100. And also the stability, transfer frequency, and recombination of its segregants obtained from curing agent treatment were studied. Ethidium bromide, acridine orange, and mitomycin-C were used as curing agent. The results obtained were as follows ; 1. The curing agent ethidium bromide, acridine orange, and mitomycin-C were not effective for curing the multiple antibiotic resistant determinant of pSL100 in Salmonella typhimurium and Escherichia coli. However, they induced plasmid segregation with high frequency in S.typhimuruim LT-2strains. TcApSmCm, TcSmCmKm, TcApCm, TcAp, TcKm, Tc segregants were obtained. 2. The resistant markers of the segregents were transferred to S.typhimurium LT-2 strains with high frequencies whereas they were transferred to E.coli K-12 only with low frequencies. 3. The transconjugants obtained from conjugation between two different S.typhimurium segregants were similar to the phenotype of the original R factor pSL100 and the resistant markers were transferred to the S.typhimurium LT-2 or E.coli strain with equal frequencies, indicating that they are recombinants. 4. The transconjugants obtained from conjugation between pSL100 segrgants and pKM101, or pBR322 possessed the resistant markers of the two parental plasmids and they were transferred to both S.typhimurium and E.coli K-12 strains with the same frequencies and maintained stably, suggesting that they are also recombinants. 5. The recombinant pSL100 could be also obtained in rec A-strains of E.coli, suggesting that the gene function of rec A is required for the recombination of pSL100 segregants in E.coli.

• Journal of Microbiology and Biotechnology
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• v.24 no.3
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• pp.421-426
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• 2014

To characterize the extended-spectrum beta-lactamases (ESBLs) in diarrheagenic Escherichia coli from Korea in 2008-2011, we screened seven enterotoxigenic E. coli (ETEC) and one enteroaggregative E. coli (EAEC) that produce ESBLs from a nationwide survey. All eight isolates produced CTX-M-type ESBLs, including CTX-M-12 (n = 4), CTX-M-14 (n = 2), and CTX-M-15 (n = 2). PCR-based replicon typing indicated that the $bla_{CTX-M-12}$ genes of four ETEC isolates were carried on a conjugative IncF plasmid, whereas the $bla_{CTX-M-14}$ of one EAEC was located on an IncK plasmid. This is the first report of the occurrence of $bla_{CTX-M}$ genes in clinical isolates of EAEC in Korea. The ESBL-producing isolates were shown to be different based on pulsed-field gel electrophoresis and multilocus sequence typing, whereas the four isolates with CTX-M-12 were clonally related. These observations raise an alarm for the spread of plasmid-mediated resistance to ESBL among diarrheagenic E. coli.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.4
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• pp.361-369
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• 1997

A microbiological nitrate determination method by E. coli is modified in Korea, using K12 wildtype, KCTC 1116, for the quantitative reduction of $NO_3{^-}$ to $NO_2{^-}$. The nitrate in plant, soil or water sample is determined spectrophotometrically after being diazotized with sulfaniamide and N-(1-naphthl)-ethlenediamine. The modified E. coli cell method and principle for nitrate determination using Korean wildtype E. coli strain is described, and cell culture and preparation of stock suspension for E. coli as well. This modified E. coli cell method can be managed simply and fast, it is suitable for the investigation of the large serials, it can be also automated and has a high degree of sensitivity up to 0.01ppm $NO_3{^-}-N$ in the sample solution. The applicability of the modified E. coli cell method has been tested for plant, soil and water analysis on a wide range of different samples. Recovery rates of added nitrate have been determined and comparisons with other standard nitrate analytical procedures have been carried out. The results with the modified E. coli cell method show high correlation ($r^2=0.98$) with those gained by the standard analytical procedures. The advantages and disadvantages of the method are also discussed to other nitrate determination methods.

• Journal of Veterinary Clinics
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• v.24 no.4
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• pp.636-639
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• 2007

Septicemic polyserositis and navel ill associated with Escherichia coli were reported in a 14-day-old male thoroughbred foal. The horse died after showing 12-day history of anorexia, lethargy, lameness and endophthalmus. Grossly, milky yellow abscesses were occupied in umbilicus, umbilical vein and artery. Large amounts of turbid pale yellow fluids were seen in pericardial sac, thoracic and abdominal cavity. Yellowish fibrinous materials were also presented in thoracic and abdominal cavity. Sticky pale yellow fluid and fibrinous materials were filled in stifle joint cavities of both hind limbs. Histologically, fibrino-purulent polyserositis and arthritis were observed. Severe omphalophlebitis with intra-lesional Gram negative bacterial colonies were noted in umbilical vein. Most of mesothelial cells in serosal cavities were severely hypertrophied. Pathogenic E. coli was purely isolated from ascites, thoracic and synovial fluids. Based on the results, the septicemic polyserositis may be originated from the umbilical cord infected with E. coli in this foal.

• Food Science and Preservation
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• v.15 no.2
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• pp.300-305
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• 2008

We investigated an antibacterial substance produced by Bacillus subtilis HS 25. Antibacterial activity was relatively heat-stable, with no effect caused by heating at $100^{\circ}C$ for 10 min, but a gradual decrease in activity after 15 min at $100^{\circ}C$. The antibacterial substance was more stable at pH 7.42-12 than at pH 4.5-5.0. There was strong antibacterial activity against E. coli and P. mirabilis at pH 12. The minimum inhibition concentration (MIC) of the substance was 5 mg/mL for E. coli 7.5 mg/mL for P. mirabilis and S. aureus and 15 mg/mL for S. enteritidis, K. pneunoniae, and V. parahaemolyticus. When the substance was added to cultures of E. coli, S. enteritidis, and P. mirabilis, the bacterial surfaces became irregular and deeply changed. The substance produced from B. subtilis HS 25 was not degraded by Papain but was degraded by a protease from Aspergillus orzae, pancreatin, and pepsin.

• Journal of Microbiology and Biotechnology
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• v.27 no.12
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• pp.2141-2150
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• 2017

This study was conducted to develop a screening method using Colilert-18 and a device for the detection of E. coli from agri-food production environments and fresh vegetables. The specificity and sensitivity of Colilert-18 by temperature ($37^{\circ}C$ and $44^{\circ}C$) were evaluated with 38 E. coli and 78 non-E. coli strains. The false-positive rate was 3.8% (3/78) and 0% (0/78) at $37^{\circ}C$ and $44^{\circ}C$, respectively. The detection limit of E. coli at $37^{\circ}C$ at <1.0 log CFU/250 ml was lower than that at $44^{\circ}C$. The efficiency of the developed device, which comprised an incubator equipped with a UV lamp to detect E. coli in the field, was evaluated by measuring the temperature and UV lamp brightness. The difference between the set temperature and actual temperature of the developed device was about $1.0^{\circ}C$. When applying the developed method and device to various samples, including utensils, gloves, irrigation water, seeds, and vegetables, there were no differences in detection rates of E. coli compared with the Korean Food Code method. For sanitary disposal of culture samples after experiments, the sterilization effect of sodium dichloroisocyanurate (NaDCC) tablets was assessed for use as a substitute for an autoclave. The addition of one tablet of NaDCC per 50 ml was sufficient to kill E. coli cultured in Colilert-18. These results show that the developed protocol and device can efficiently detect E. coli from agri-food production environments and vegetables.

• Journal of Microbiology and Biotechnology
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• v.25 no.1
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• pp.137-142
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• 2015

Trimethoprim-sulfamethoxazole (TMP-SMX) has been used for the treatment of urinary tract infections, but increasing resistance to TMP-SMX has been reported. In this study, we analyzed TMP-SMX resistance genes and their relatedness with integrons and insertion sequence common regions (ISCRs) in uropathogenic gram-negative bacilli. Consecutive nonduplicate TMP-SMX nonsusceptible clinical isolates of E. coli, K. pneumoniae, Acinetobacter spp., and P. aeruginosa were collected from urine. The minimal inhibitory concentration was determined by Etest. TMP-SMX resistance genes (sul and dfr), integrons, and ISCRs were analyzed by PCR and sequencing. A total of 45 E. coli (37.8%), 15 K. pneumoniae (18.5%), 12 Acinetobacter spp. (70.6%), and 9 Pseudomonas aeruginosa (30.0%) isolates were found to be resistant to TMP-SMX. Their MICs were all over 640. In E. coli and K. pneumoniae, sul1 and dfr genes were highly prevalent in relation with integron1. The sul3 gene was detected in E. coli. However, in P. aeruginosa and Acinetobacter spp., only sul1 was prevalent in relation with class 1 integron; however, dfr was not detected and sul2 was less prevalent than in Enterobacteriaceae. ISCR1 and/or ISCR2 were detected in E. coli, K. pneumoniae, and Acinetobacter spp. but the relatedness with TMP-SMX resistance genes was not prominent. ISCR14 was detected in six isolates of E. coli. In conclusion, resistance mechanisms for TMP-SMX were different between Enterobacteriaceae and glucose non-fermenting gram-negative bacilli. Class 1 integron was widely disseminated in uropathogenic gram-negative baciili, so the adoption of prudent use of antimicrobial agents and the establishment of a surveillance system are needed.

• Journal of Microbiology and Biotechnology
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• v.23 no.12
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• pp.1708-1716
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• 2013

Conventional molecular detection methods cannot distinguish between viable and dead Escherichia coli O157 cells. In this study, the loop-mediated isothermal amplification (LAMP) method combined with propidium monoazide (PMA) treatment was developed to selectively detect viable E. coli O157 cells. Four primers, including outer primers and inner primers, were specially designed for the recognition of six distinct sequences on the serogroups (O157) of the specific rfbE gene of the E. coli O157 genome. PMA selectively penetrated through the compromised cell membranes and intercalated into DNA. Amplification of DNA from dead cells was completely inhibited by $3.0{\mu}g/ml$ PMA, whereas the DNA derived from viable cells was amplified remarkably within 1 h by PMA-LAMP. Exhibiting high sensitivity and specificity, PMA-LAMP is a suitable method for evaluating the inactivation efficacy of slightly acidic electrolyzed water in broth. PMA-LAMP can selectively detect viable E. coli O157 cells. This study offers a novel molecular detection method to distinguish between viable and dead E. coli O157 cells.