• Journal of the Korean Vacuum Society
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• v.7 no.s1
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• pp.44-49
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• 1998

The antimicrobial effects of HAp and Ag-HAp was observed using periprosthetic infection bacteria such as Pseudomonas Aeruginosa, Staphylococcus Epidermidis, Escherichia coli (DH5$\alpha$). Ag-HAp showed good antimicrobial effects. TEM study of E. coli with and without Ag treatment in HAp was experimented in order to find the mechanism of Ag in antimicrobial effects. It was observed that the shape of Ag-treated E. coli was changed, the cells walls became inhomogeneous. The vaculoes at cytoplasm formed into E. coli and finally it was discovered by EDAX that there were many dark granules which contain the Ag element inside the cells.

• Food Science and Preservation
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• v.16 no.1
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• pp.128-133
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• 2009

We performed an experiment of keeping the extension of raw and semi-dried flounder (Pleuronectes herzensteini). The effect of with (WG) or without gill (OG), drying degree (20% drying: 20D, 40% drying: 40D) and storage temperature($5^{\circ}C$) and 0.1% chitosan-ascorbate (CA) treatment of vacuum packaging flounder on the growth of contaminated microorganism during storage for 10 days were investigated. Total aerobacter (TA) in the OG-treated raw flounder was $0.29{\sim}0.44$ log cycle lower than that of WG-treated flounder. Also, the number of Staphylococcus aureus (SA) and E. coli (EO) in OG were lower compared with WG. The number of TA, SA and EO in 20 D among 0 D, 20 D and 40 D stored at $5^{\circ}C$ were lowest. Especially, the SA and EO was $0.13{\sim}0.53$, 0.3-0.88, and 0.13-0.74 log cycle lower compared with raw flounder. The growth of TA, SA and EO separated from raw flounder in tryptic soy broth were completely inhibited by 0.1% CA. The anti-biotical effect of CA of two microorganisms SA and EO that separated from flounder, and the growth of all of them were 90% (SA), 96% (EO) inhibited at the 0.1% CA. The inhibition times at $37^{\circ}C$ in soy broth was 36 hr. However when CA was added directly to flounder, it appeared inhibition effect to 0.88 log cycle. The effect of CA was better when gills removed and 20% drying.

• Journal of Microbiology and Biotechnology
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• v.30 no.10
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• pp.1552-1558
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• 2020

With an increase in the consumption of non-heated fresh food, foodborne shiga toxin-producing Escherichia coli (STEC) has emerged as one of the most problematic pathogens worldwide. Endolysin, a bacteriophage-derived lysis protein, is able to lyse the target bacteria without any special resistance, and thus has been garnering interest as a powerful antimicrobial agent. In this study, rV5-like phage endolysin targeting E. coli O157:H7, named as LysECP26, was identified and purified. This endolysin had a lysozyme-like catalytic domain, but differed markedly from the sequence of lambda phage endolysin. LysECP26 exhibited strong activity with a broad lytic spectrum against various gram-negative strains (29/29) and was relatively stable at a broad temperature range (4℃-55℃). The optimum temperature and pH ranges of LysECP26 were identified at 37℃-42℃ and pH 7-8, respectively. NaCl supplementation did not affect the lytic activity. Although LysECP26 was limited in that it could not pass the outer membrane, E. coli O157: H7 could be effectively controlled by adding ethylenediaminetetraacetic acid (EDTA) and citric acid (1.44 and 1.14 log CFU/ml) within 30 min. Therefore, LysECP26 may serve as an effective biocontrol agent for gram-negative pathogens, including E. coli O157:H7.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.2
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• pp.164-167
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• 2006

The influence of temperature and agitation on the growth of Escherichia coli expressing hepatitis B core antigen (HBcAg) in stirred tank bioreactor were investigated. The highest specific growth rate for E. coli$(0.844 h^{-1})$ was achieved at a temperature of $37^{\circ}C$ and an agitation speed of 250 rpm. The activation energy for the growth of the E. coli strain W3110lQ in the stirred tank bioreactor was estimated to be 11 kcal/mol. The highest protein yield was achieved at a temperature of $44^{\circ}C$ and an agitation speed of 250 rpm. The relative protein concentration at $44^{\circ}C$ is 30 and 6% higher compared to that at 30 and $37^{\circ}C$, respectively.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.526-533
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• 2019

The purpose of this study was to investigate hazardous microorganisms in mixed baby leafy vegetables and various baby leafy vegetables used as raw materials for fresh-cut produce in spring and summer. To estimate microbial loads, a total of 298 samples including 181 samples of mixed baby leafy vegetables purchased in a Korean market and 117 samples of various baby leafy vegetables from distribution companies were collected. Fecal indicators (coliform and Escherichia coli) as well as food-borne pathogens (E. coli O157:H7, Salmonella spp., Staphylococcus aureus) were enumerated. As a result, the mixed baby leafy vegetable samples showed significantly higher (P<0.05) coliform bacteria numbers in summer (5.59±1.18 log CFU/g) compared to spring (3.60±2.53 log CFU/g). E. coli was detected in 1.3% (1/79) and 42.2% (43/102) of samples collected in spring and summer, respectively. Only one sample collected from a market in spring was contaminated with S. aureus. In the experiment with baby leafy vegetables, the number of coliforms detected in baby leafy vegetables cultivated in soil in spring was 1.15±1.95 log CFU/g, and that in summer was 4.09±2.52 log CFU/g. However, the number of coliforms recovered from baby leafy vegetables cultivated in media was above 5.0 log CFU/g regardless of season. Occurrences of E. coli were 44.4% (12/27) and 19.0% (4/21) for baby leafy vegetables cultivated in soil and media, respectively. However, E. coli O157:H7 and Salmonella spp. were not detected. These results are in relation to microbial loads on mixed baby leafy vegetables associated with raw materials. Therefore, it is necessary to develop and implement hygienic practices at baby leafy vegetable farms to enhance the safety of fresh produce.

• Biomedical Science Letters
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• v.21 no.2
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• pp.84-91
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• 2015

To provide guidelines for the empirical treatment of urinary tract infections, we observed annual changes in the occurrence frequency and antimicrobial susceptibility of urinary isolates in a university hospital in the Chungbuk province, South Korea, over a period of 10 years (2004~2013). Escherichia coli (38.2%), Enterococcus faecalis (11.7%), Klebsiella pneumoniae (7.3%), Pseudomonas aeruginosa (4.3%), E. faecium (4.3%), and Staphylococcus aureus (4.1%) were commonly isolated urinary pathogens. The prevalence of E. coli, E. faecium and Streptococcus agalactiae were significantly higher in females (P < 0.001), whereas E. faecalis, P. aeruginosa and S. aureus were significantly more common in male patients (P < 0.001). E. coli mostly frequently showed resistance to ampicillin (67.94%), followed by trimethoprim/sulfamethoxazole (36.06%) and ciprofloxacin (26.84%). Over the studied time period, resistance rates of E. coli to ciprofloxacin significantly increased (20.44% to 33.55%). Moreover, extended-spectrum $\beta$-lactamase (ESBL) producing isolates also significantly increased in E. coli (4.2% to 18.3%) and K. pneumoniae (9.6% to 26.9%). In addition, the proportion of vancomycin-resistant Enterococcus facium (VRE) also increased (15.7% to 25.0%). In conclusion, over the last 10 years, the proportions of ciprofloxacin resistant E. coli and multidrug-resistant bacteria, such as ESBL and VRE have significantly increased. This trend must be strictly controlled and demonstrates the need for more updated guidelines for the treatment of urinary tract infections.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.85-93
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• 2017

The urinary tract infection (UTI) is one of the most important infections in hospital. The overuse and misuse of antimicrobial agents and the resulting emergence of resistant microorganisms have made choices regarding antimicrobial therapy more difficult. This study examined the changes in the antibiotic susceptibility to the causative organisms of urinary tract infections to provide useful information on the choice of adequate drugs in the treatment of urinary tract infections. The medical records of 2,707 patients with more than $10^5/ml$ microorganism in urine culture between January 2010 and December 2015 were reviewed retrospectively. The most common pathogenic organism was E. coli (28.1%). In the case of E.coli, there were no differences in frequency from 2010 to 2015 in men, but since 2014, the frequency decreased gradually since 2014 in women. For E. coli, the resistance rates to antibiotics were 72.2% in ampicillin, 44.9% in trimethoprim/sulfamethoxazole (TMP/SMX), and 41.3% in ciprofloxacin, but the 2nd, 3rd, and 4th cephalosporin (5%) had low antibiotic resistance rates. The pathogens of urinary tract infection are becoming diverse and their frequencies are also changing over time. These results suggest that the recommended drugs for UTI should be selected more carefully for in-patients and out-patients.

• Korean Journal of Veterinary Service
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• v.30 no.1
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• pp.103-113
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• 2007

We monitored antibiotic resistance of Escherichia coli isolates from healthy volunteers of community and chicken butchers from February to July in 2006. From disc diffusion test on 473 E coli isolates from healthy volunteers of the community, the resistance rates of tetracycline, ampicillin, and ticarcillin were 44.8%, 40.8%, and 37.4%, respectively. In the disc diffusion test on 18 E coli isolates from chicken butchers, the resistance rates of tetracycline, nalidixic, streptomycin, and ampicillin were 94.4%, 61.1%, 55.6%, and 50.0%, respectively.

• Microbiology and Biotechnology Letters
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• v.30 no.1
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• pp.1-7
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• 2002

Phytase from Escherichia coli WC7 was purified from cell extracts and its molecular mass was estimated to be 45 kDa by SDS-PAGE. Its optimum temperature and pH for phytate hydrolysis was 6$0^{\circ}C$ and pH 5.0, respectively. The enzyme was stable up to 6$0^{\circ}C$ and over broad pH range (pH 2-12). The enzyme had higher affinity for sodium phytate than p-nitrophenylphosphate (pNPP). That is, the apparent Km value for sodium phytate and pNPP were $0.15\pm$0.02 mM and 2.82$\pm$0.05 mM, respectively. The gene encoding the phytase was cloned in E. coli XL1-Blue. Sequence analysis showed an open reading frame of 1241 Up encoding a signal peptide (22 aa) and a mature enzyme (410 aa). WC7 phytase was expressed up to 17.5 U/ml in the transformed E. coli XL1-Blue/pUEP, which was 23-fold higher than the activity from wild strain.

• Korean Journal of Veterinary Research
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• v.50 no.3
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• pp.231-237
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• 2010

This study was conducted to investigate characteristics and antimicrobial susceptibility of Escherichia (E.) coli isolates isolated from vaginal mucosa and clitorial fossa of 105 Thoroughbred mares suspicious of the genital disease in Korea during the period from March 2006 to July 2007. Ninety six E. coli isolates were identified as standard biochemical properties and using BIOLOG system. Fifty three isolates (55.2%) could be classified into a total of 21 O serotypes and forty three isolates (44.8%) were non-typeable with 51 O antisera used in this study. The verotoxin 1 (VT 1) and verotoxin 2 genes were analyzed by multiplex PCR. Among them, one isolate was detected VT 1 gene (130 bp). Most of isolates showed a high susceptibility in ciprofloxacin (100%), enrofloxacin (100%), norfloxacin (100%), cefoxitin (96.9%), gentamicin (96.9%), sulphamethoxazole (96.9%), nitrofurantoin (94.8%), amikacin (93.8%), nalidixic acid (92.7%) and tetracycline (90.6%). These results may provide the basic information to establish strategies for the treatment and prevention of reproductive disease in Thoroughbred mares in Korea.