• Korean Journal of Veterinary Service
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• v.40 no.1
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• pp.27-33
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• 2017

Salmonella enterica subsp. enterica is a common microbial flora in pet turtles, which could opportunistically become pathogenic to human. Their possession of aminoglycoside resistance genes has important significance both in humans and animal medicine. In this study, twenty-one Salmonella enterica subsp. enterica were isolated from thirty-five individual turtles purchased from pet shops and online markets in Korea. In order to characterize the aminoglycoside susceptibility patterns, antimicrobial susceptibility tests were performed against gentamicin, amikacin and kanamycin of aminoglycoside antimicrobial group. Each of the isolates showed susceptibility to all tested aminoglycosides in disk diffusion and minimum inhibitory concentration (MIC) tests. PCR assay was carried out to determine aminoglycoside resistance genes, integron and integron mediated aminoglycoside genes. None of the isolates showed aac(3)-IIa, aac-(6')-Ib, armA, aphAI-IAB aminoglycoside resistance genes. Only, five isolates (24%) harbored class 1 integron related IntI1 integrase gene. The results suggest that Salmonella enterica subsp. enterica strains isolated from pet turtles are less resistance to aminoglycosides and don't harbor any aminoglycosides resistance genes.

• Microbiology and Biotechnology Letters
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• v.19 no.4
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• pp.372-379
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• 1991

A rapid and simple quantitative assay method for aminoglycoside-3'- phosphotransferase (APH(3')) derived from E. coli ATCC 21990 was developed using the thin layer chromatographic densitometry, 3'-phosphorylated kanamycin B (3'-PKMB), product of APH (3') reaction, was separated from reaction mixtures by developing on the silica gel TLC plate with chloroform-methanol-ammonia water (3:4:3). The quantity of the 3'-PKMB was measured by densitometry after color development by ninhydrin method. Densitometric TLC assay for APH (3') was showed a good quantitative result and reproducibility. Sensitivity of this assay was 1.56 nmol of 3'-PKMB and could be analyzed many samples at same time. This method may be applicable for the analysis of inactivating enzymes of aminoglycoside antibiotics.

• Journal of Microbiology and Biotechnology
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• v.12 no.1
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• pp.18-24
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• 2002

The present study was performed to investigate the excellent microbial anticaries substance, aminoglycoside antibiotic, which is more effective than chlorhexidine for the treatment of dental caries. The aminoglycoside antibiotic against Streptococcus mutans JC-2 from a novel alkaliphilic Bacillus alkalophilshaggy JY-827 exhibited no significant difference at the treatment concentration of $2.5{\times}10^{-7}M$, however, it inhibited the activity of the Streptococcus mutans glucosyltransferase by 70.2% and 99.8% at the concentrations of $2.5{\times}10^{-7}$M\;and\;2.5{\times}10^{-6}M$, respectively. Lineweaver-Burk plot of the inhibitory aminoglycoside antibiotic showed competitive inhibition, with $K_i$ value of $6.4{\times}10^{-6}$ M. The aminoglycoside antibiotic did not show any cytotoxicity against human gingival cells. To evaluate the industrial applicability of the aminoglycoside antibiotic, a toothpaste containing this substance was prepared and tested on the extracted human teeth. The inhibitory rate of tooth calcification and calcium ion elution by the aminoglycoside antibiotic were 50% and 2.5 times, respectively. These results suggested that the aminoglycoside antibiotic from Bacillus alkalophilshaggy JY-827 is an effective agent against dental caries.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.2
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• pp.136-142
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• 2020

The antimicrobial resistance rate in bacteria has increased over the last several decades. The transfer of antimicrobial resistant determinants on mobile genetic elements could cause the accelerated emergence and spread of multidrug resistant bacteria. This study investigated the aminoglycoside resistance determinants transferred by mobile genetic elements in a total of 33 aminoglycoside non-susceptible E. coli isolated from clinical specimens in Chungcheong province. 16S ribosomal RNA methyl-transferases (RMTases) and aminoglycoside-modifying enzyme (AME) genes were detected via PCR and DNA sequencing. The most common AME genes were aac(3')-II gene (54.5%), followed by aph(3')-Ia (18.2%) and aac(6')-Ib (15.2%). None of the evaluated RMTase genes were detected in the 33 isolates. Seventeen of the 18 isolates harboring aac(3')-II gene were resistant to gentamicin, and 16 of them were resistant to tobramycin. The 5 isolates harboring aac(6')-Ib gene were all resistant to tobramycin. In this study, we confirmed that one of the important mechanisms of aminoglycoside resistance in E. coli isolated from human is the acquisition of AME genes. Continuing investigations of antimicrobial resistant determinants in bacteria isolated from human may be required to prevent dissemination of antimicrobial resistant bacteria.

• Journal of Microbiology and Biotechnology
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• v.13 no.5
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• pp.828-831
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• 2003

Although most of the DOS containing aminoglycosides are produced by Streptomyces, very little information is available about their biosynthesis. In the present paper, we report a method to isolate DOI synthase, a key enzyme in the biosynthesis of DOS, from aminoglycoside producer Streptomyces. PCR primers based on conserved region of DOI synthases were specific and reliable for the isolation of the biosynthetic genes of DOS containing aminoglycosides or the screening of the aminoglycoside producers. The use of DOI synthase as a probe could save both time and cost of cloning aminoglycoside biosynthetic genes.

• Microbiology and Biotechnology Letters
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• v.19 no.5
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• pp.491-496
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• 1991

To maximize the production of aminoglycoside-3'-phosphotransferase of E. coli ATCC 21990 carrying R factor which encodes aminoglycoside-3'-phosphotransferase (APH(3')) phosphorylating the 3'-hydroxyl group of aminoglycoside, mutants M1 and M2, media composition and several factors affecting the enzyme production during fermentation were studied. Although the specific activity of APH(3') produced by a mutant M1 was increased as much as four times than that of E. coii ATCC 21990, the growth rate was decreased. The increase of the enzyme production was obtained by increased biomass during fermentation. A mutant M2 was obtained to increase the cell growth rate. Mutant M2 cells were cultivated with optimal media and pure oxygen gas in a fed-batch mode of fermentor operation. The specific activity of APH(3') was decreased, but total enzyme activity of APH(3') was increased as much as two point five times than that of mutant MI.

• Journal of the Korean Magnetic Resonance Society
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• v.6 no.1
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• pp.69-77
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• 2002

During the screening of material which has the antimicrobial activity against aminoglycoside-resistant bacteria, A new material $\varepsilon$-(L-$\beta$-Iysine) polypeptide from a culture medium of Streptomyces sp.(DWGS2) was isolated, and the structure and the physicochemical properties of the new material were elucidated. The new material was separated by column chromatography of the culture medium using Dowex1$\times$2, Silica gel, and Sephadex LH20 etc. The chemical structure and molecular weight were determined with the data of various NMR experiments, MALDI mass, and ESI mass experiments. The antimicrobial activity of $\varepsilon$-(L-$\beta$-Iysine) polypeptide is not only better than equal to the activity of known aminoglycoside type of antibiotics(MIC=3.125 - 6.25ug/mL) but also effective against aminoglycoside-resistant bacteria and fungi. If the mechanism of antimicrobial activity against aminoglycoside- resistant bacteria is figured out, the $\varepsilon$-(L-$\beta$-Iysine) polypeptide can be utilized for the treatment of diseases caused by aminoglycoside-resistant bacteria.

• Microbiology and Biotechnology Letters
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• v.27 no.3
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• pp.215-222
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• 1999

Methylotrophic actinomycetes No. 155 produced an aminoglycoside antibiotics(AG)-resistant inhibitor. We have previously reported that the inhibitor shows strong inhibition to sisomicin-resistant strain. In order to understand the functions of inhibitor and sisomicin-resistance, characterizations and purification of inhibitor were investigated. Strain No. 155 was tentatively identified as Nocardiopsis sp. based on morphological and some physiological characteristics. In the antimicrobial activity test, the addition of inhibitor to sisomicin showed a reduction effect of MIC on the test strains such as Gram(+), Gram(-) bacteria and yeasts. The combination of the inhibitor and various antibiotics revealed synergistic against E. coli K-12 and B. subtilis PCI 219. The induced intracellular proteins from sisomicin-resistant strain exhibited the sisomicin inactivation by invitro test. And the induced intracellular proteins were inactivated by addition of the inhibitor. The inhibitor compound was purified by anion exchange chromatography(Dowex-1) and HPLC using Asahipak ES-502C column. The purified inhibitor compound was detected in a single peak(above 98.5% purity) through the HPLC analysis.

• The Journal of the Korean Society for Microbiology
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• v.21 no.3
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• pp.375-380
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• 1986

Thirty-one strains of Pseudomonas aeruginosa were submitted to the synergistic activity test of amikacin(AK) and gentamicin(GM) combined with moxalactam(MX), ceftizoxime(CTZ) or cefoperazone(CFZ). The minimal inhibitory concentrations(MICs) of each drug and drugs combined in various ratios were measured by checkerboard dilution method. The synergism was determined through analysing the MIC distribution curve on isobologram and calculating the fractional inhibitory concentration index(FICI). MICs of GM, AK, MX, CFZ and CTZ against the 31 tested strains were distributed from $12.5{\mu}g/ml$ to $800{\mu}g/ml$, from $0.8{\mu}g/ml$ to $25{\mu}g/ml$, from $3.1{\mu}g/ml$ to $50{\mu}g/ml$, from $3.1{\mu}g/ml$ to $400{\mu}g/ml$, and from $12.5{\mu}g/ml$ to $100{\mu}g/ml$, respectively. The rate synergism of each drug combination by means of FICl was 45.5% in GM-MX, 36.4% in GM-CFZ, 63.6% in GM-CTZ, 48.6% in AK-MX, 35.3% in AK-CFZ, and 35.7% in AK-CTZ combination. Thus, it is suggested that Pseudomonas aeruginosa may effectively be inhibited by various aminoglycoside and cephalosporin combinations.

• Archives of Pharmacal Research
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• v.12 no.4
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• pp.249-253
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• 1989

High producers or blocked mutants of aminoglycoside antibiotic-producing Streptomyces spp. were selected by application of an agar plug method and by culturing individual colonies in broth. The productivities of aminoglycoside antibiotic producing organisms were increased by selection of a high producer from colonies obtained by spreading spores of wild strain, or survived from treatment of a mutagen or from the colonies regenerated from protoplast-formation and cell-wall regenerations. Some mutagen treated colonies lost the ability to produce antibiotics (5-8%). Some A-factor negative and deostreptamine or streptidine negative mutants were obtained by N-methyl-N'-nitro-N-nitrosomethylguanidine (MNNG) treatment. Many of the survivors from the MNNG treatment lost the ability to produce antibiotics. Major colonies produced less amount of antibiotics ; only few survived colonies produced more antibiotics than the parent. Resistance of Streptomyces spp. against the antibiotics produced by itself was also markedly affected by mutagen treatment.