• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.04a
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• pp.26-32
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• 2000

• BMB Reports
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• v.31 no.4
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• pp.328-332
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• 1998

The 8-hydroxyisocoumarin, named Centipedin, which has a significant antibiotic activity, was separated and solubilized with organic solvents, such as diethyl ether from centipede Scolopendra subspinipes multilans L. Koch. The Centipedin was purified by silicic acid column and high S cation exchange chromatography followed by reverse-phase HPLC. It was confirmed that Centipedin has a potent antibiotic effectiveness against Gram-negative Klebsiella pneumoniae ATCC 8308. The results showed that Centipedin blocks both DNA replication and RNA transcription during the growth of this pathogen in vivo. The biosynthesis of antibiotic 8-hydroxyisocoumarin was studied in vivo by feeding $[^{14}C]-labelled$ compound as a precursor to live centipede, in which $[^{14}C]acetate$ was the most efficiently incorporated into the Centipedin within 30 h after injection. Also, in vitro study on the biosynthesis of Centipedin showed that efficient incorporation of $[^{14}C]acetate$ occurred at pH range 5.0-7.0 for 10 h incubation and decreased significantly after then. It is suggested that 8-hydroxyisocoumarin is one of the defense compounds acting on bacterial infection in Scolopendra subspinipes.

• BMB Reports
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• v.56 no.6
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• pp.326-334
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• 2023

Antibiotic resistance (AR) is a silent pandemic that kills millions worldwide. Although the development of new therapeutic agents against antibiotic resistance is in urgent demand, this has presented a great challenge, especially for Gram-negative bacteria that have inherent drug-resistance mediated by impermeable outer membranes and multidrug efflux pumps that actively extrude various drugs from the bacteria. For the last two decades, multidrug efflux pumps, including AcrAB-TolC, the most clinically important efflux pump in Gram-negative bacteria, have drawn great attention as strategic targets for re-sensitizing bacteria to the existing antibiotics. This article aims to provide a concise overview of the AcrAB-TolC operational mechanism, reviewing its architecture and substrate specificity, as well as the recent development of AcrAB-TolC inhibitors.

• Microbiology and Biotechnology Letters
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• v.32 no.4
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• pp.312-316
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• 2004

In oder to select the powerful rhizophere-dorminatable biocontrol agent, we had isolated an indigenous antagonistic bacterium which produced antibiotic and siderophore from a disease suppressive local field soil of Gyungsan, Korea. And we could select the Pseudomosp. 4059 which can strongly antagonize against Fusarium oxysporum and Phytophthora capsici by two kinds of antifungal mechanism that can be caused by the antibiotic of Phenazin, a siderophore and a auxin like subThe selected strain was identified as Pseudomonas fluorescens (biotype A) 4059 by biochemical tests, API $\textregistered$ test, MicroLog TM system and 16S rDNA analysis. The selected antagonistic microorganism, Pseudomosp. 4059 had an antifungal mechanism of antifungal antibiotic and sidrophore. And we were confirmed the antagonistic activity of P fluorescens 4059 with in vitro antifungal test against Phytophthora capsici and in vivo by red-pepper.

• Journal of Convergence for Information Technology
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• v.10 no.4
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• pp.104-114
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• 2020

We investigated the best antibiotics using blending oils after screening 11 kinds of essential oil known as antibiotics from plants. The minimum inhibitory concentration (MIC) and the minimum killing concentration (MBC) were found to be essential for essential oils B and E to inhibit target bacteria. All gram-positive bacteria containing S. aureus used in this experiment were shown highly antibiotic activity. And only A. baumanii in gram-positive bacteria and C. albicans in fungi were shown highly antibiotic activity. The essential oils used in our experiments showed better antibiotic activity compared to major studies using natural antibiotics with excellent antibiotic activity and essential oils from natural medicine. It is not known what mechanism of antimicrobial activity the essential oil used in the test has, but it is interpreted as a synthetic inhibitory mechanism of cell wall compared with other previous studies. From these results, it is expected that some substances or functional products with antibiotic activity will be developed.

• Biomolecules & Therapeutics
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• v.31 no.2
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• pp.141-147
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• 2023

Antibiotic resistance has emerged as a global threat to modern healthcare systems and has nullified many commonly used antibiotics. β-Lactam antibiotics are among the most successful and occupy approximately two-thirds of the prescription antibiotic market. They inhibit the synthesis of the peptidoglycan layer in the bacterial cell wall by mimicking the D-Ala-D-Ala in the pentapeptide crosslinking neighboring glycan chains. To date, various β-lactam antibiotics have been developed to increase the spectrum of activity and evade drug resistance. This review emphasizes the three-dimensional structural characteristics of β-lactam antibiotics regarding the overall scaffold, working mechanism, chemical diversity, and hydrolysis mechanism by β-lactamases. The structural insight into various β-lactams will provide an in-depth understanding of the antibacterial efficacy and susceptibility to drug resistance in multidrug-resistant bacteria and help to develop better β-lactam antibiotics and inhibitors.

• Korean Journal of Microbiology
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• v.34 no.1_2
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• pp.31-36
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• 1998

A broad spectrum of antibiotic action was studied with Centipedin purified from centipede Scolopendra subspinipes multilans L. Koch aganist gram-positive, gram-negative bacteria and fungi. The minimal inhibitory concentrations(MICs) were determined in liquid medium. The significant antibiotic activity was obtained aganist gram-negative Klebsiella pneumoniae ATCC 8308 responsible for causing infection at lung and intestine. The MIC value against Klebsiella pneumoniae ATCC 8308 was $2{\mu}g/ml$, and this Centipedin was active against Proteus vulgaris NRRL B-123. In addition, it has been shown that Centipedin blocks procaryotic RNA transcription and a little of DNA replication system in vitro. Centipedin did not exhibit any significant cytotoxicity against animal cells such as human blood leukemia (HL-60) and mouse B lymphocyte myeloma cell.

• BMB Reports
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• v.33 no.4
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• pp.332-336
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• 2000

Phenazine 1-carboxylic acid (PCA) is an antifungal antibiotic isolated from a culture filtrate of Bacillus sp. B-6 producing an acyl CoA synthetase inhibitor. This antibiotic is reported as an inhibitor of an acyl CoA synthetase from Pseudomonas sp.. Bacillus sp. B-6 was resistant to PCA up to 350 ${\mu}g/ml$. We investigated the mechanism of the resistance of Bacillus sp. B-6 to PCA. The rate of growth in a medium containing up to 100 ${\mu}g/ml$ was as rapid as the PCA-free medium. At a PCA concentration of 300 ${\mu}g/ml$, the growth rate was more than half that of the control. In this work, we purified acyl CoA synthetase from Bacillus sp. B-6 and found that this acyl CoA synthetase was much less sensitive to PCA than the acyl CoA synthetase from other source. These findings suggested that the insensitivity of Bacillus sp. B-6 acyl CoA synthetase plays an important role in the PCA resistance of this bacterium.

• BMB Reports
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• v.38 no.5
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• pp.507-516
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• 2005

Antimicrobial peptides (AMPs) have been isolated and characterized from tissues and organisms representing virtually every kingdom and phylum. Their amino acid composition, amphipathicity, cationic charge, and size allow them to attach to and insert into membrane bilayers to form pores by 'barrel-stave', 'carpet' or 'toroidal-pore' mechanisms. Although these models are helpful for defining mechanisms of AMP activity, their relevance to resolving how peptides damage and kill microorganisms still needs to be clarified. Moreover, many AMPs employ sophisticated and dynamic mechanisms of action to carry out their likely roles in antimicrobial host defense. Recently, it has been speculated that transmembrane pore formation is not the only mechanism of microbial killing by AMPs. In fact, several observations suggest that translocated AMPs can alter cytoplasmic membrane septum formation, reduce cell-wall, nucleic acid, and protein synthesis, and inhibit enzymatic activity. In this review, we present the structures of several AMPs as well as models of how AMPs induce pore formation. AMPs have received special attention as a possible alternative way to combat antibiotic-resistant bacterial strains. It may be possible to design synthetic AMPs with enhanced activity for microbial cells, especially those with antibiotic resistance, as well as synergistic effects with conventional antibiotic agents that lack cytotoxic or hemolytic activity.

• Journal of environmental and Sanitary engineering
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• v.10 no.2
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• pp.74-78
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• 1995

Several reports have suggested that these hydrolases( chitlnase, glucanase ) are likely volved in defense reactions in this Plant. In this paper, Induction by ethylene, mechanism, properties and function for Activation of these enzymes were Summarized.