• Journal of Food Hygiene and Safety
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• v.11 no.4
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• pp.315-321
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• 1996

Various antimicrobial drug screen tests have been used in order to ensure food safety. However, the conventional screen tests, the Swab Test on Premises(STOP, USA), the Calf Antibiotic and Sulfa Test(CAST, USA) and the European Economic Community 4-plate Test(FPT, EU) are not sufficiently rapid or sensitive enough to detect low levels of sulfa drugs in meat. We developed a new screen test kit for the determination of the antimicrobial residues in meat called the Bacillus megaterium Disk Assay(BmDA). A comparison of BmDA with the older screen tests showed BmDA was as good as the older ones with several advantages. The new test kit is faster-it can be read in 4∼6 hours instead of 16∼18 hours. Moreover, BmDA can discriminate sulfa drugs from other antimicrobial drugs because p-aminobenzoic acid countacts the inhibiting action of sulfa drugs. Minimum detectable levels of sulfa drugs were significantly improved at the lever of 0.025*0.1 pp, compared with the level of 1.0 ppm in FPT. A comparison of BmDA with the older screen tests in HPLC confirmed meat samples exceeded the Korean tolerance value of 0.1 ppm showed BmDA was the most sensitive in the microbiological screen tests. As the microbiological screen tests have already known, a person familiar with simple laboratory techniques should have no difficulty in using it to detect antimicrobial residues in meat. This would be a simple, economic method of antimicrobial residues detection which might be succesfully used by many laboratories.

• Journal of Food Hygiene and Safety
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• v.11 no.4
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• pp.307-314
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• 1996

The European Economic Community four plate test(EEC 4-plate test, FPT, EU) has been used for monitoring antimicrobial drug residues in meat by Local Veterinary Service Center in Korea. This study was performed to evaluate sensitivity and group specificity of some antimicrobial drugs in FPT and to compare FPT with Charm II test. The minimal detectable levels of targeted antimicrobial drugs tested with standard solutions were 0.025∼1.0 ppm for 7 beta-lactams, 0.5∼1.0 ppm for 4 aminoglycosides, 0.05∼0.5 ppm for 5 macrolides, 0.05∼0.25 ppm for 3 tetracyclines and 0.25&1.0 ppm for 6 sulfonamides. In comparison of FPT and Charm II test, the results of FPT were not accord with those of Charm II test having the group specificity of seven families of antimicrobial drugs in meat samples except some families like tetracyclines.

• Korean Journal of Veterinary Service
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• v.31 no.1
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• pp.129-135
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• 2008

A total of 3,943 samples (beef 698, pork 2,178 and chicken 1,067)were collected from slaughter houses in Daegu from January to December 2006 for analysis of antimicrobial residues. The results were also comparatively analyzed with those carried out from 16 veterinary service laboratories nationwide as a part of national residue program in 2006. The samples from 11 farms (cattle 2, pig 9) were found to exceed the legal limit. Among them 5 were classified as tetracyclines, 3 as $\beta$-lactams, 2 as sulfonamides and 1 as quinolone. Nationally a total of 222 farms (241 cases) were found to violate the residual limits, of which 47.3% were detected by screening test, followed by surveillance (38.3%). Failure to observe withholding periods of antimicrobial drugs after treatment was the most significant cause of the non-compliance.

• Journal of Microbiology and Biotechnology
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• v.24 no.2
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• pp.160-167
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• 2014

Oligopeptidase B (OpdB) is a serine peptidase widespread among bacteria and protozoa that has emerged as a virulence factor despite its function has not yet been precisely established. By using an OpdB-overexpressing Escherichia coli strain, we found that the overexpressed peptidase makes the bacterial cells specifically less susceptible to several proline-rich antimicrobial peptides known to penetrate into the bacterial cytosol, and that its level of activity directly correlates with the degree of resistance. We established that E. coli OpdB can efficiently hydrolyze in vitro cationic antimicrobial peptides up to 30 residues in length, even though they contained several prolines, shortening them to inactive fragments. Two consecutive basic residues are a preferred cleavage site for the peptidase. In the case of a single basic residue, there is no cleavage if proline residues are present in the $P_1$ and $P_2$ positions. These results also indicate that cytosolic peptidases may cause resistance to antimicrobial peptides that have an intracellular mechanism of action, such as the proline-rich peptides, and may contribute to define the substrate specificity of the E. coli OpdB.

• BMB Reports
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• v.30 no.3
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• pp.229-233
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• 1997

Indolicidin has been known to have a broad spectrum of antimicrobial activities against Gram negative and positive bacteria. Its eight analogues were chemically synthesized. The analogue design was based on the analysis of sequence to elucidate the role of some residues in the antibacterial mechanism of indolicidin. Bactericidal activities were assayed against Escherichia coli and Proteus vulgaris, and the membrane perturbing abilities of the peptides were assayed using a dye containing liposome. Among the eight analogues, $[Gly^4, Gly^6]-Indo,\;[Ile^6,Ile^8]-Indo,\;[Lys^{12}]-Indo$ and $[Thr^2,Tyr^9]-Indo$ showed enhanced antibacterial activities. These results suggest that proline and cationic residues are important in the bactericidal activity of indolicidin. We tried to describe the antimicrobial mechanism of indolicidin with these results.

• Bulletin of the Korean Chemical Society
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• v.30 no.8
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• pp.1839-1844
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• 2009

A 20-residue hybrid peptide CA(1-8)-MA(1-12) (CAMA) incorporating residues 1-8 of cecropin A (CA) and residues 1-12 of magainin 2 (MA) has high antimicrobial activity without toxicity. To investigate the effects of the total positive charges of CAMA on the antibacterial activity and toxicity, a hybrid peptide analogue (CAMA-syn) was designed with substitutions of $Ile^{10}\;and\;Ser^{16}$ with Lys. According to CD spectra, structure of CAMA-syn with increase of cationicity was very similar to that of CAMA in DPC micelle. CAMA-syn showed antimicrobial activity similar with CAMA while CAMA-syn has no hemolytic activity and much lower cytotoxicity against RAW 264.7 macrophage cells than CAMA. Also, CAMA and CAMA-syn significantly inhibited NO production by LPSstimulated RAW264.7 macrophage at 10.0∼20.0 $\mu$M. CAMA-syn displayed salt resistance on antimicrobial activity against Escherichia coli at the physiological concentrations of $CaCl_2\;and\;MgCl_2$. The combination studies of peptides and antibiotics showed that CAMA-syn has synergistic effects with synthetic compound and flavonoid against Enterococcus faecalis and VREF. CAMA-syn can be a good candidate for the development of new antibiotics with potent antibacterial and synergistic activity but without cytotoxicity.

• Journal of Microbiology and Biotechnology
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• v.30 no.9
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• pp.1305-1309
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• 2020

Insects possess biological defense systems that can effectively combat the invasion of external microorganisms and viruses, thereby supporting their survival in diverse environments. Antimicrobial peptides (AMPs) represent a fast-acting weapon against invading pathogens, including various bacterial or fungal strains. A 37-residue antimicrobial peptide, papiliocin, derived from the swallowtail butterfly Papilio xuthus larvae, showed significant antimicrobial activities against several human pathogenic bacterial and fungal strains. Jelleines, isolated as novel antibacterial peptides from the Royal Jelly (RJ) of bees, exhibit broad-spectrum protection against microbial infections. In this study, we developed a novel antimicrobial peptide, PAJE (RWKIFKKPFKISIHL-NH₂), which is a hybrid peptide prepared by combining 1-7 amino acid residues (RWKIFKK-NH₂) of papiliocin and 1-8 amino acid residues (PFKISIHL-NH₂) of Jelleine-1 to alter length, charge distribution, net charge, volume, amphipaticity, and improve bacterial membrane interactions. This novel peptide exhibited increased hydrophobicity and net positive charge for binding effectively to the negatively charged membrane. PAJE demonstrated antimicrobial activity against both gram-negative and gram-positive bacteria, with very low toxicity to eukaryotic cells and an inexpensive process of synthesis. Collectively, these findings suggest that this novel peptide possesses great potential as an antimicrobial agent.

• Food Science of Animal Resources
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• v.28 no.1
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• pp.59-62
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• 2008

The aim of this work was to assess the Delvo test for the detection of antimicrobial residues in goat milk. A total of fifty six samples (eight farms, seven samplings each) were analyzed by the Delvo, Eclipse 100, and Parallux tests. None of the samples showed positive results with the Parallux test which is based on immune-chemical methods. However, 37.5% of samples showed positive results with the Delvo test. 3.6% of samples showed positive results with the Eclipse 100 test, which is based on a microbiological method. The Delvo test is included in the 'standard methods for the examination of raw milk' by the National Veterinary Research and Quarantine Service as a microbiological method used for the detection of antimicrobial residues. Because "raw milk" is defined as 'milked state of cow, ewe and goat milk for sale or for processing' in the Animal Food Products Processing Law, the Delvo test should be excluded from the 'standard method for the examination of raw milk', or additional official documents referring to the Delvo test as not appropriate for the detection of antimicrobial residues of goat milk are required.

• Asian-Australasian Journal of Animal Sciences
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• v.9 no.1
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• pp.27-30
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• 1996

One thousand eight hundreds and twenty two samples of raw milk were detected for antibiotic residues using Bacillus subtilis ATTCC 6633, B. stearothermophilus var. calidolactis C 593 and Micrococcus luteus ATCC 9341 as test organisms, were carried out from July 1991 through June 1992. Apparent antibiotic residues were found through out the study period, except in January. The detection rate varied from 0.7% in March and May to 11% in April. One hundred and thirty six (72%) samples of the 187 screening positive samples were considered to contain only the indigenous antimicrobial agents. Of the total, 51 (2.8%) samples were positive for antibiotic residues. Among the tested organisms, B. stearothermophilus var. calidolactis was the most sensitive organism in detection of the antibiotic residues.

• Journal of the Korean Magnetic Resonance Society
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• v.15 no.1
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• pp.1-13
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• 2011

9Pbw2 is a 9-mer analog of protaetiamycine derived from the larvae of the beetle Protaetia brevitarsis. Previously, we designed four 9-mer peptide analogues to optimize the balance between the hydrophobicity and cationicity of the peptides and to increase bacterial cell selectivity. Among them, 9Pbw2 has high antibacterial activity without cytotoxicity. The results obtained in previous study suggest that the bactericidal action of 9Pbw2 may be attributed to the inhibition of the functions of intracellular components after penetration of the bacterial cell membrane. In order to understand structure-activity relationships, we determined the three-dimensional structure of 9Pbw2 in 200 mM DPC micelle by NMR spectroscopy. 9Pbw2 has one hydrophobic turn helix from $Trp^3$ to $Arg^8$ and positively charged residues at the N- and C-terminus. This result suggested that positively charged residues from position at the C-terminus in 9Pbw2 may be important for the primary binding to the negatively charged phospholipid head groups in bacterial cell membranes and hydrophobic residues in the middle portion face toward the acyl chains of the hydrophobic lipid in the bacterial cell membrane.