• 한국환경농학회지
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• 제25권3호
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• pp.262-267
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• 2006

Increased application of glyphosate (Gly) in glyphosate-resistant (GR) soybean cropping systems may affect rhizospheric microorganisms including IAA-producing rhizobacteria (IPR) and their effect on the growth of soybean. This field experiment was conducted to assess IPR populations in the rhizosphere of GR soybean ('Roundup-Ready' DeKalb DKB38-52) treated with glyphosate and foliar amendment treatments such as $PT21^{(R)}$ (urea solution with N 21 %) and $Grozyme^{(R)}$ (Biostimulant: mixtures of micro nutrients and enzymes). Effects of herbicide, sampling date, and their interaction on total bacterial numbers were significant (P < 0.001, 0.001, 0.013, respectively). Total bacteria (TB) numbers were increased with glyphosate treatment at 20 d after application and highest TB populations were associated with $Grozyme^{(R)}$ application, possibly due to the additional substrate from this product. The IPR of the soybean rhizosphere was significantly affected by herbicide, sampling date, and the herbicide*foliar amendment interaction. The ratios of numbers of IPR to TB ranged from 0.79 to 0.99 across the sampling dates irrespective of treatments. IPR numbers were slightly hindered by glyphosate application regardless of foliar amendment.

• 한국미생물·생명공학회지
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• 제42권2호
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• pp.152-161
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• 2014

The in vitro antimicrobial potential of the unexplored Moringa oleifera seed coat (SC) was evaluated against some Gram-positive and Gram-negative bacteria and yeast pathogens. Antimicrobial studies with various solvent extracts indicated ethyl acetate to be the best extractant, which was used for the rest of the antimicrobial studies as it tested neither toxic nor mutagenic. Gram-positive bacteria including a methicillin resistant Staphylococcus aureus (MRSA) strain were more susceptible with a minimum inhibitory concentration (MIC) range of 0.03-0.04 mg/ml. The antimicrobial pharmacodynamics of the extract exhibited both concentration-dependent and time-dependent killing. Most of the test organisms exhibited a short post antibiotic effect (PAE) except Enterococcus faecalis, Staphylococcus aureus, and Klebsiella pneumoniae 1, which exhibited longer PAEs. Amongst the major phytoconstituents established, flavonoids, diterpenes, triterpenes and cardiac glycosides exhibited inhibitory properties against most of the test organisms. The identified active phytochemicals of the M. oleifera seed coat exhibited antimicrobial potential against a wide range of medically important pathogens including the multidrug-resistant bugs. Hence, the M. oleifera seed coat, which is usually regarded as an agri-residue, could be a source of potential candidates for the development of drugs or drug leads of broad spectrum that includes multidrug-resistant bugs, which are one of the greatest concerns of the $21^{st}$ century.

• The Plant Pathology Journal
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• 제35권5호
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• pp.486-497
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• 2019

Citrus canker is a devastating disease of citrus caused by Xanthomonas citri subsp. citri (Xcc). A total of 134 endophytic bacteria were isolated from various gymnospermic and angiospermic plants. They were screened for their antagonistic activities against three wild-type and six streptomycin-resistant Xcc strains. TbL-22 and TbL-26, both later identified as Bacillus thuringiensis, inhibited all the wild and resistant Xcc strains. TbL-22 exerted the highest antagonistic activity against XccW3 and XccM6 with inhibition zones of $20.64{\pm}0.69$ and $19.91{\pm}0.87mm$, respectively. Similarly ethyl acetate extract of TbL-22 showed highest inhibition zones $15.31{\pm}2.08$ and $19.37{\pm}3.17mm$ against XccW3 and XccM6, respectively. TbL-22 reduced canker incidence on infected leaves by 64.05% relative to positive controls. Scanning electron microscopy revealed that the cell membranes of Xcc treated with ethyl acetate extract of TbL-22 were ruptured, lysed, and swollen. B. thuringiensis TbL-22 can effectively and sustainably controls streptomycin-resistant citrus canker.

• Preventive Nutrition and Food Science
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• 제15권1호
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• pp.74-77
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• 2010

Antibiotic-resistant Staphylococcus aureus is beginning to pose a social issue. Thus, there is an urgent need for the development of effective anti-staphylococcal agents to eradicate antibiotic-resistant S. aureus in food systems and to treat the pathogen in clinical areas. To address this need, lactic acid bacteria (LAB) from kimchi were screened for the production of anti-staphylococcal bacteriocin. From this screening, a bacteriocin generated by the MK3 strain, which was identified by 16S rRNA gene sequence analysis as Enterococcus faecium, demonstrated antimicrobial activity against an S. aureus strain, and was designated enterocin MK3. Enterocin MK3 also demonstrated activity against other gram-positive bacteria, including several LAB and Listeria monocytogenes, but not gram-negative Escherichia coli. The molecular mass of enterocin MK3 was estimated as approximately 6.5 kDa on an SDS-PAGE (sodium dodecyl sulfate-polyacrylamide gel electrophoresis) gel.

• Fisheries and Aquatic Sciences
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• 제3권3_4호
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• pp.217-221
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• 2000

In previous study, marine actinomycetes producing the antibiotics were investigated to invent new antibiotics from east coast of Korea. The optimum growth conditions of Streptomyces sp. NS 13239 were $28^{\circ}C$, pH 7.0 and $3\%$ of NaCl concentration in various media. Streptomyces sp. NS 13239 showed strong antimicrobial activity against gram-positive bacteria, specially Methicillin resistant Staphylococcus aureus (MRSA), but just weak antimicrobial activity against yeasts and mold. On the other hand, it did not show antimicrobial activity against gram-negative bacteria. The optimum conditions for producing antibiotics were almost consistent with optimum growth conditions except carbon source and nitrogen source.

• Archives of Pharmacal Research
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• 제22권1호
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• pp.25-29
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• 1999

Psammaplin A, a natural bromotyrosine derivative from an associated form of two sponges (Poecillastra sp. and jaspis sp.) was found to possess the antimicrobial effect on the Gram-positive bacteria, especially on methicillin-resistant Staphylococcus aureus (MRSA). The minimal inhibitory concentration of psammaplin A against twenty one MRSAs ranged from 0.781 to 6.25 ${\mu}g/ml$, which that of ciprofloxacin was 0.391~3.125${\mu}g/ml$. Psammaplin A could not bind to penicillin binding protein, but inhibited the DNA synthesis and the DNA gyrase activity with the respective 50% (DNA synthesis) and 100% (DNA gyrase) inhibitory concentration 2.83 and 100 ${\mu}g/ml$. These results indicate that psammaplin A has a considerable antibacterial activity, although restricted to a somewhat narrow range of bacteria, probably by inhibiting DNA gyrase.

• Journal of Dairy Science and Biotechnology
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• 제37권1호
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• pp.40-48
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• 2019

Bifidobacteria are a prototype probiotic, which normally inhabit the intestinal tract of humans. In the present study, four species of Bifidobacterium isolated from the feces of infants were characterized. The tolerance for acid or bile salt, autoaggregation, and antibiotic resistance of the bacteria were examined. The four species were resistant to low pH, bile salts, and up to 3% bile acid. Autoaggregation rates were as high as 90%. The bacteria were consistently resistant to gentamicin, kanamycin, streptomycin, ciprofloxacin, and nalidixic acid. Due to their tolerance to environmental factors like acid and bile salts, B. longum MG723, B. breve MG729, B. bifidum MG731, and B. animalis subsp. lactis MG741 are potentially valuable as probiotics and may be useful for industrial application.

• Clinical and Experimental Pediatrics
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• 제62권4호
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• pp.113-118
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• 2019

Inappropriate antibiotic use is the most important factor causing increased bacterial resistance to antibiotics, thus affecting patient outcomes. Multidrug-resistant bacteria have become a serious public health threat, causing significant morbidity and mortality worldwide. In Korea, the burden of antibiotic-resistant bacteria has become an important public health issue. There is increasing evidence of overuse and misuse of antibiotics in Korea, as observed in cohorts with large sample sizes. Antibiotic use among children should receive particular attention because of the frequency of community-associated infections among this population and the elevated risk of transmission. Recent studies from Korea have demonstrated that the use of broad-spectrum antibiotics, either for inpatient or outpatient treatment, has increased among many age groups, especially children. In this review, we aim to describe the patterns of antibiotic prescription and evaluate recent trends in antibiotic use among children. Coordinated efforts toward communication and education in order to address misunderstandings regarding antibiotic use, involving interprofessional antimicrobial stewardship programs, are required in the near future.

• Journal of Microbiology
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• 제45권4호
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• pp.358-363
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• 2007

Multi-drug resistant Pseudomonas aeruginosa has been implicated in a variety of serious therapeutic problems in clinical environments. Among the 968 P. aeruginosa isolates obtained from two hospitals in Daegu, Korea, we acquired 17 isolates that were resistant to all available tested antimicrobial agents, with the exception of colistin (colistin-only sensitive). We characterized the antimicrobial susceptibilities, $metallo-{\beta}-lactamases$, and epidemiological relatedness among the colistin-only sensitive P. aeruginosa isolates. All colistin-only sensitive isolates were positive in the modified Hodge test and imipenem-EDTA synergy test, thereby indicating the production of $metallo-{\beta}-lactamases$. 11 isolates from the secondary hospital and six isolates from the tertiary teaching hospital harbored $bla_{VIM-2}$ and $bla_{IMP-1}$, respectively. The pulsed-field gel electrophoretic analysis of the SpeI-digested DNA from P. aeruginosa isolates indicated that two different clones of colistin-only sensitive P. aeruginosa originated from each hospital, and had spread within the hospital environment. Overall, colistin-only sensitive P. aeruginosa was detected in Korea for the first time, but no pan-drug resistant bacteria were identified. Nationwide surveillance is required in order to monitor the emergence of colistin-only sensitive or pan-drug resistant bacteria.

• Journal of Microbiology and Biotechnology
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• 제8권4호
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• pp.388-398
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• 1998

A bacterium which is resistant to both mercury and cadmium, and also capable of utilizing phenol as a carbon and energy source, was isolated from the Kumho River sediments near Kangchang Bridge, Taegu, Korea. The isolate was labeled Pseudomonas sp. KM10 and characterized. The bacteria grew in 4 mM $CdCl_2$and in $70{\mu}M$ $HgCl_2$. The bacteria efficiently removed over 90% of 1 g/l phenol within 30 h. In the presence of 1.250 g/l phenol, the growth of the microorganism was slightly retarded and the microorganism could not tolerate 1.5 g/l phenol. Curing of plasmid from the bacteria was carried out to generate a plasmidless strain. Subsequent experiments localized the genes for phenol degradation in plasmid and the genes for mercury resistance and cadmium resistance on the chromosome. Dot hybridization and Southern hybridization under low stringent conditions were performed to identify the DNA homology. These results showed significant homologies between the some sequence of the chromosome of Pseudomonas sp. KM10 and merR of Shigella flexneri R 100, and between the some sequence of the chromosome of Pseudomonas sp. KM10 and cadA of Staphylococcus aureus pI258. The mechanism of cadmium resistance was efflux, similar to that of S. aureus pI258 cadA, and the mechanism of mercury resistance was volatilization, similar to that of S. flexneri R100 mer.