• Journal of Food Hygiene and Safety
• /
• v.18 no.2
• /
• pp.79-86
• /
• 2003

Most of food poisoning is frequently raised from mass catering. Especially, staphylococci takes the large part of pathogenic agents which are related to the hygienic condition. Among total 98 samples, four staphylococci were isolated from food service environment such as drinking water (A), hands (D), refrigerator and apron (E) of 5 elementary school (A, B, C, D, E) in Gyeongnam Province. These isolated strains are characterized as 1 MRCNS (Methicilline Resistant Coagulase Negative Staphylococcus aureus) and 3 MSCPS (Methicilline Sensitive Coagulase positive Staphylococcus aureus). Also, production of enterotoxin B (sob gene) were examined by PCR which has known as a big problem because of their temperature resistance. Hence, PCR was performed on isolated 4 staphylococci. The all 4 isolated Staphylococcus aureus have 477 bp of seb gene. Antibiotics susceptibility test was completed on PCR detected strains. All strains were fully resistance to ampicillin and penicillin. The drinking water of A place has resistance to oxacilline, therefore this strain turned out to be MRSA (Methicilline Resistant Staphylococcus Aureus).

• Journal of Microbiology and Biotechnology
• /
• v.19 no.2
• /
• pp.178-186
• /
• 2009

To examine their potential as probiotics, acid and bile tolerance, antibiotics resistance, adhesion capacity to Caco-2 and HT-29, and antibacterial activity, of LAB isolated from Korean fermented foods such. as dongchimi, kimchi, Meju, and doenjang were assayed against foodborne pathogenic bacteria. DC 55, DC 136, DC 222, KC 21, KC 24, KC 34, KC 43, KC 117, MJ 54, MJ 301, SP 33, and SP 170 strains were resistant to acid and bile conditions. In particular, DC 55, DC 136, KC 24, KC 43, and MJ 301 strains were highly resistant to higher than 20 ${\mu}g/ml$ concentrations of vancomycin, streptomycin sulfate, or amoxicillin, whereas, DC 222, KC 21, KC 34, KC 117, MJ 54, and SP 33 strains were susceptible to lower than 2 ${\mu}g/ml$ concentrations of those antibiotics. The adhesion to HT-29 and Caco-2 cells varied with the strains tested in a strain-dependent manner. The highest level of adhesion was observed with DC 55, KC 21, KC 24, and MJ 301 strains, having higher than 50% of adhesion to HT-29 or Caco-2 cells. In addition, Staphylococcus aureus was the most sensitive to KC 21, showing an inhibition of about 70%, and the antibacterial activity of KC 21 against S. aureus resulted most likely from both organic acids and bacteriocin. Based on its phenotypic characteristics and utilization of various sugars, the KC 21 strain was identified as Lactobacillus plantarum.

• Korean Journal of Organic Agriculture
• /
• v.23 no.3
• /
• pp.497-507
• /
• 2015

It is necessary to evaluate the resistance to disease among genetic resources for development of disease resistant grapes. This study was conducted to screen the resistance to crown gall in muscadine and Florida hybrid bunch grapes by pathogen inoculation. In order to compare the responses to infection with different pathogen strains, muscadine and Florida hybrid grapes were inoculated with 3 strains of Agrobacterium vitis. Although there were different levels crown gall formation among grape cultivars, there little variation in response to inoculated strains. Among 29 muscadine cultivars tested by inoculation of A. vitis 'C4612', most of them were shown to be susceptible, and 'Gold Isle' and 'Africa Queen' were highly susceptible, and two cultivars, 'Welder' and 'Jumbo' were found to be resistant to crown gall disease. Among Florida hybrid grapes, 'Daytona', 'Stover', and 'Swanee' were susceptible and 'Blanc du Bois' was moderately susceptible to crown gall. Because muscadine grapes have been actively utilized as useful genetic resources for development of new grape varieties by intersub-genus cross, this result from the screening of resistance among muscadine grapes can provide valuable information in breeding programs of grape resistant to crown gall.

• The Journal of the Korean Society for Microbiology
• /
• v.22 no.2
• /
• pp.147-153
• /
• 1987

Colonization factor antigen I(CFA I) has been shown to be one of several virulence factors that promote attachment of enterotoxigenic E. coli(ETEC) to small intestinal epithelial cells of humans. The ability of ETEC to produce mannose-resistant hemagglutination(MRHA) of human blood group A has been used to detect CFA I. To determine gastrointestinal carriage in Korean children of E. coli with MRHA and CFA I, 116 strains of E. coli from diarrheal children admitted to Hanyang University Hospital were examined for MRHA of human erythrocytes and the presence of CFA I. Of 45 ETEC strains, 18(40%) gave a positive MRHA($MRHA^+$) and eight(18%) were positive for CFA I(CFA $I^+$). ETEC with CFA I were all heat-stable enterotoxin(ST) producers and two of these strains were of serogroups $O_{25}$. Of 17 classic enteropathogenic E. coli(EPEC), 7(41%) were $MRHA^+$ but all were negative for CFA I(CFA $I^-$). Of 30 enteroadherent E. coli(EAEC) strains, 11(37%) were $MRHA^+$ and one was CFA $I^+$. Of 24 nonpathogenic E. coli, 4(17%) were $MRHA^+$ but all were CFA $I^-$. It was shown that MRHA was common in all strains of E. coli, CFA I was limited only to ST producing ETEC and EAEC; although MRHA is a useful screening procedure, serologic tests seem to be necessary to comfirm CFA I production. CFA I was associated with a lower proportion of ETEC isolates in Korea than has been reported for other locations.

• Microbiology and Biotechnology Letters
• /
• v.50 no.4
• /
• pp.584-591
• /
• 2022

Identifying carbapenem-resistant Enterobacteriaceae (CRE) is necessary to prevent nosocomial CRE infection outbreaks. Here, a rapid identification method with reduced enrichment time was developed without compromising accuracy. A total of 49 rectal swabs requested for CRE screening at the Department of Diagnostic Medicine at Hospital B in Busan, Korea, were included in this study. Specimens were inoculated on MacConkey and CHROMID Carba media either directly or following enrichment for 3, 6, and 24 h in 100 μl trypticase soy broth containing an ertapenem disk. The enriched cultures were further inoculated on CHROMID Carba or MacConkey media containing an ertapenem disk. In total, 19 CRE and 5 carbapenem-intermediate Enterobacteriaceae isolates were obtained from the 49 swabs. Among the 19 CRE isolates, carbapenemase-producing Enterobacteriaceae constituted 13 strains. Moreover, of the 19 CRE isolates, 16 (81.25%) and 17 (88.24%) were identified from the direct cultures on MacConkey and CHROMID Carba media, respectively. After 3 h of enrichment, the proportions of the CRE identified in the media were: MacConkey medium, 16/19 (81.25%); CHROMID Carba medium, 17/19 (88.24%); and MacConkey medium containing an ertapenem disk, 17/19 (88.24%). The detection rates after 6 h of enrichment were the same for all three media (19/19 strains, 100%), whereas those after 24 h of enrichment were 21, 22, and 24 strains, respectively, but included false positives. These findings suggest that a 6-h enrichment before inoculation on the CHROMID Carba medium is optimal for the rapid and accurate detection of CRE in clinical samples.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.5
• /
• pp.942-945
• /
• 2008

There have been concerns about possible pathogenicity and antimicrobial resistance in Enterococcus, which constitute more than 50% of probiotics in the worldwide market. In this study, Enterococcus in sixteen products manufactured by ten different companies was tested for the presence of six virulence genes and two vancomycin resistance genes. Results in this study showed the safety of Enterococcus on the Korean market and the importance of screening vanA, vanE, agg, cylA, esp, and gelE. Pulse-field gel electrophoresis showed that the sixteen isolates tested in this study are originated from three strains.

• YAKHAK HOEJI
• /
• v.46 no.2
• /
• pp.108-112
• /
• 2002

Drug resistance is one of the most significant impediments to successful chemotherapy of cancer. Multidrug-resistance (MDR) is characterized by decreased cellular sensitivity to anticancer agents due to the overexpression of P-glycoprotein. By employing a resistant subline of HCT15 to adriamycin (CL02), we undertook the screening for agents which were effective to multidrug-resistant cancer cells. As a result, a myxobacterial strain JW150 was selected for study since an activity against CL02 cells was discovered in the strain. Cytotoxicity-guided fractionation of the culture broth led to the isolation of cystothiazole A and melithiazole F. The producing organism was identified as Myxococcus stipitatus by taxonomic comparison with type strains of Myxococcus sp. as well as its morphological and physiological characteristics. Cystothiazole A and melithiazole F demonstrated potent cytotoxicity against certain human cancer cells with $IC_{50}$ values ranging from 0.03~ $0.72{\mu}{\textrm{g}}$/ml. Both compounds were interestingly as active against drug-resistant sublines CL02 and CP70 as against the corresponding parental cells.

• Genomics & Informatics
• /
• v.20 no.4
• /
• pp.47.1-47.13
• /
• 2022

Klebsiella pneumoniae is a gram-negative bacterium that is known for causing infection in nosocomial settings. As reported by the World Health Organization, carbapenem-resistant Enterobacteriaceae, a category that includes K. pneumoniae, are classified as an urgent threat, and the greatest concern is that these bacterial pathogens may acquire genetic traits that make them resistant towards antibiotics. The last class of antibiotics, carbapenems, are not able to combat these bacterial pathogens, allowing them to clonally expand antibiotic-resistant strains. Most antibiotics target essential pathways of bacterial cells; however, these targets are no longer susceptible to antibiotics. Hence, in our study, we focused on a hypothetical protein in K. pneumoniae that contains a DNA methylation protein domain, suggesting a new potential site as a drug target. DNA methylation regulates the attenuation of bacterial virulence. We integrated computational-aided drug design by using a bioinformatics approach to perform subtractive genomics, virtual screening, and fingerprint similarity search. We identified a new potential drug, koenimbine, which could be a novel antibiotic.

• Food Science of Animal Resources
• /
• v.31 no.3
• /
• pp.405-412
• /
• 2011

The purpose of this study was to isolate and characterize bacteriocin-producing bacteria against Clostridium perfringens from domestic animals to determine their usefulness as probiotics. The feces of cattle and chicken were used as sources to isolate bacteriocin-producing bacteria using the spot-on-lawn method. In total, 900 bacterial stains were isolated from domestic animal feces, and 19 strains were finally selected after determining the inhibitory activity against the pathogenic indicator C. perfringens KCTC 3269. Eighteen strains of Bacillus subtilis and one strain of Brevibacillus parabrevis were identified by 16s rRNA sequencing. Most of the bacterial strains isolated were resistant to 0.5% bile salts and remained viable after 2 h at pH 3.0. Additionally, some B. subtilis strains showed strong inhibitory activity against Listeria monocytogenes. We isolated and screened B. subtilis strains CB 153 and CB 189 from cattle and B. subtilis MSC 156 and B. parabrevis MSC 164 from chickens using probiotic selection criteria such as inhibition activity against C. perfringens and tolerance to acid and bile salts. The isolated bacteriocin-producing bacteria and/or bacteriocin have the potential to be used as probiotics in the livestock industry.

• KSBB Journal
• /
• v.20 no.5 s.94
• /
• pp.376-382
• /
• 2005

Avermectin (AVM) $B_{1a}$ produced by Streptomyces avermitilis via polyketide pathway is a secondary metabolite with powerful anthelmintic and insecticidal activities, thus being used as an efficient agent in the field of agriculture and animal health. It has been reported that a precursor for AVM $B_{1a}$ biosynthesis was isoleucine and the biosynthetic pathway of AVM $B_{1a}$ was closely similar to that of fatty acid. Based on understanding of the biosynthetic pathway of AVM $B_{1a}$, we intended to screen various mutants resistant against O-methyl threonine (OMT), an isoleucine-anti metabolite, and/or mutants resistant against p-fluoro phenoxy acetic acid (pFAC), an inhibitor of fatty acid biosynthesis. It was inferred that these mutants could produce AVM $B_{1a}$ more efficiently, due to the acquired capability of not only overproducing isoleucine intracellularly but also channelling metabolized carbon-sources into the polyketide pathway, thus leading to enhanced biosynthesis of AVM $B_{1a}$. The resulting mutant (PFA-1 strain) resistant against 100 ppm of pFAC was able to produce approximately 42 fold higher amount of AVM $B_{1a}$ compared to the parallel mother strain (4,200 vs. 100 units/l). In addition, through the process of continuous strain improvement program carried out by gradually increasing the OMT concentration, it was possible to obtain a more attractive mutant with greater AVM $B_{1a}$ production capacity (9,000 units/l). Notable was that significantly higher producer (12,000 units/l) could be selected through further screening of the resistant mutants, this time, to even higher concentration of PFAC. Meanwhile, through the analysis of AVM Bla production histograms (i.e., number of strains according to their AVM $B_{1a}$ biosynthetic ability) for the earlier strains in comparison with the high producers having the characteristics of resistance to OMT and pFAC, it was found that production stability of the high-yielding producers were remarkably improved, as demonstrated by the fact that larger proportion of the mutated strains had greater capability of AVM $B_{1a}$ biosynthesis ($71\%$ in the range between 5,000 and 7,000 units/L; $47\%$ in the range between 6,000 and 7,000 units/l). Based on these consequences, it was concluded that the rational screening strategy based on the understanding of the biosynthetic pathway of AVM $B_{1a}$ was very effective in obtaining high-yielding mutants with the features of enhanced production stability.