• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.251-256
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• 2011

We screened for antibacterial substances against methicillin-resistant Staphylococcus aureus (MRSA). Methanolic extract of Eisenia bicyclis exhibited anti-MRSA activity according to a disk diffusion assay. To identify the active compound(s), the methanolic extract was further fractionated using hexane, dichloromethane, ethyl acetate, and n-butanol. The ethyl acetate-soluble fraction showed both the greatest anti-MRSA activity and the highest polyphenol content. The minimum inhibitory concentrations of the ethyl acetate fraction ranged from 32 to 64 ${\mu}g$ per mL against methicillin-susceptible S. aureus and MRSA strains. High-performance liquid chromatography analysis revealed that both the methanolic extract and the ethyl acetate soluble fraction contained sizeable quantities of dieckol, which is a known anti-MRSA compound. Thus, these data strongly suggest that the anti-MRSA activity of E. bicyclis may be mediated by phlorotannins such as dieckol.

• Korean Journal of Veterinary Service
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• v.36 no.4
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• pp.283-289
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• 2013

The antibiotic chemotherapy produces sometimes side effects and fails to eliminate bacterial infection. The occurrence of strains resistant to antibiotics would be expected to increase, and it is nowadays important to search for non-antibiotic substances. We are aimed to evaluate the effects of Torilis fructus extracts against enteropathogenic Escherichia coli (E. coli) in Piglets. The piglets were divided with three groups; Negative control group, E. coli-infected positive control group, and the Torilis fructus extracts treated group with E. coli infection. During the study period, we compared clinical signs, weight increase rate, fecal scores, gross findings between the treated group and non treated group. After necropsy, necropsy findings and histopathological findings were conducted with the comparison between the groups. As the results of this study, the Torilis fructus extracts additive showed the effects on the suppression of E. coli-induced lesions. On the basis of this study results, our data suggest that the Torilis fructus extracts additive have the antimicrobial effects. The Torilis fructus extracts additive could be used as the alternative material for antimicrobial feed additives.

• Journal of Microbiology
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• v.45 no.1
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• pp.6-10
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• 2007

Culture broth of a streptomycete isolate, Streptomyces sp. CS684 showed antibacterial activity on methicilin resistant Staphylococcus aureus (MRSA) and vancomycin resistant enterococci (VRE). Among purified substances from the organism, CSU-1, which is active against MRSA and VRE, is a $C_{37}H_{62}O_{12}Na\;(M^+,721.3875)$, and identified as laidlomycin. The anti-MRSA and anti-VRE activity of CSU-1 was stronger than oxacillin and vancomycin. Phylogenetic analysis showed that strain CS684 is very similar to Streptomyces ardus NRRL $2817^T$, whereas the ability of Streptomyces sp. CS684 to produce laidlomycin was shown to be unique.

• Journal of Life Science
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• v.8 no.2
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• pp.173-180
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• 1998

As a part of the investigation on useful compounds from microalgae, and its recently that marine planktonic algae have been recognized as potial sources of antibacterial and antifungal substances, we searched for antimicrobial active compounds from the extracts of six microalgae-Lyngbya sp., Tetraselmis sp., Microcystis sp., Chlorella sp., Navicula sp. and Rhalassiosira sp.-treated with several solvents. There were two active species-Lyngbya ap., Teraselmis sp.- in the antimicrobial activity test to bacteria, yeast and molds, especially the activity existed in the extracts by ethyl acetate of supernatants to the microalgae incubatio. and there won’t any activity in two diatoms to the test microorganism.

• Microbiology and Biotechnology Letters
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• v.49 no.4
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• pp.493-500
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• 2021

Argyrins are a group of anticancer and antibacterial octapeptide bioactive substances isolated from myxobacteria. In this study, we showed that the myxobacterium Archangium gephyra MEHO_001, isolated in Korea, produces argyrins A and B. MEHO_001 cells tend to aggregate when cultured in liquid media. Hence, a dispersion mutant, MEHO_002, was isolated from MEHO_001. The MEHO_002 strain produced approximately 3.5 times more argyrins than that produced by the wild-type strain MEHO_001. We determined the whole-genome sequence of A. gephyra MEHO_002 and identified a putative argyrin biosynthetic gene cluster comprising five genes, arg1-arg5, encoding non-ribosomal peptide synthases and tailoring enzymes. Inactivation of arg2 by plasmid insertion disrupted argyrin production. The amino acid sequences of the proteins encoded by arg2-arg5 of A. gephyra MEHO_002 were 90-98% similar to those encoded by the argyrin biosynthetic genes of Cystobacter sp. SBCb004, an argyrin-producing myxobacterium with identical domain organization.

• Journal of Veterinary Science
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• v.23 no.2
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• pp.23.1-23.15
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• 2022

Background: Antibacterial agents play important roles in the treatment of bacterial infections. However, the development of antimicrobial resistance (AMR) and carry-over of substances into the environment are several problems arising during oral treatment of bacterial infections. We assessed AMR development in commensal Escherichia coli (E. coli) in enrofloxacin treated and untreated animals. In addition, we examined fluoroquinolone in the plasma and urine of treated and untreated animals, and in sedimentation dust and aerosol. Methods: In each trial, six pigs were treated with enrofloxacin via powder, granulate or pellet forms in two time periods (days 1-5 and 22-26). Four pigs served as untreated controls. The minimum inhibitory concentration (MIC) was determined to evaluate AMR development. Analysis of enro- and ciprofloxacin was performed with high performance liquid chromatography. Results: Non-wildtype E. coli (MIC > 0.125 ㎍/mL) was detected in the pellet treated group after the first treatment period, whereas in the other groups, non-wildtype isolates were found after the second treatment period. E. coli with MIC > 4 ㎍/mL was found in only the pellet trial. Untreated animals showed similar susceptibility shifts several days later. Bioavailability differed among the treatment forms (granulate > pellet > powder). Enro- and ciprofloxacin were detected in aerosols and sedimentation dust (granulate, powder > pellet). Conclusions: This study indicates that the kind of the oral dosage form of antibiotics affects environmental contamination and AMR development in commensal E. coli in treated and untreated pigs.

• Microbiology and Biotechnology Letters
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• v.40 no.3
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• pp.250-260
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• 2012

In the present study, the antioxidative and antibacterial activities of Artemisia princeps Pampanini (A. princeps Pamp.) extract were investigated. The ethyl acetate fraction of A. princeps Pamp. showed the most prominent free radical (1,1-diphenyl-2-picrylhydrazyl, DPPH) scavenging activity ($FSC_{50}=12.27{\mu}g/mL$). Reactive oxygen species (ROS) scavenging activities ($OSC_{50}$) of A. princeps Pamp. extract on $Fe^{3+}-EDTA/H_2O_2$ systems were investigated using a luminol-dependent chemiluminescence assay. The ethyl acetate fraction of the extract ($OSC_{50}=0.33{\mu}g/mL$) had a 5 times greater ROS scavenging activity than L-ascorbic acid ($1.50{\mu}g/mL$), known as a water soluble antioxidant. The cellular protective effects of fractions of A. princeps Pamp. on the rose-bengal sensitized photohemolysis of human erythrocytes were examined. The aglycone fraction of extracts suppressed photohemolysis in a concentration dependent manner. The inhibitory effects of A. princeps Pamp. extract on tyrosinase were investigated to assess their whitening efficiency. The ethyl acetate fraction demonstrated a 7 times higher tyrosinase inhibitory effect ($IC_{50}=29.20{\mu}g/mL$) than albutin, known as a whitening agent. The antibacterial activity of ethyl acetate fractions against various normal skin flora were measured. The results showed that the antibacterial activity of the fraction was the highest on Staphylococcus aureus, Bacillus subtilis, and Propionibacterium acnes. Antioxidant substances were isolated and purified from the ethyl acetate fractions. Eupatilin and jaceosidin were identified. These results indicate that the extract/fractions of A. princeps Pamp. can function as antioxidant and/or antibacterial agents for the skin.

• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.238-244
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• 2007

To identify the useful biological activities and the superiority in quality of Korean traditional liquors, we prepared the alcohol-free concentrates from different types of commercial traditional liquors, Takju ($T1{\sim}T3$), Yakju/Cheongju ($Y-1{\sim}Y-5$), Fruit wine (F-1) and Soju (S-1, S-2), respectively. We investigate their compositions as well as antimicrobial, antioxidant, and anti-thrombosis activity. Among the 11 traditional liquors, Y-3, Y-4, Y-5 and F-1 showed higher total-polyphenol, total-flavonoids and reducing sugars than the others. The strong antibacterial and anti-thrombosis activities were identified in Y-3, Y-4, Y-5 and F-1, and a minor antioxidant activity was found in F-l. The antibacterial activity of the Y-3, Y-4, Y-5 and F-1 alcohol-free concentrates showed a broad-spectrum, and growth inhibition was found in gram-positive, gram-negative, and ampicillin-resistant bacteria. The sequential solvent fractionation of Y-3, Y-4, Y-5 and F-1, and following analysis showed that ethyl acetate fractions of Y-3, Y-4, Y-5 and F-1 possess strong antibacterial and anti-thrombosis activity. Especially, the ethyl acetate fractions of Y-3, Y-4 and F-1 showed superior anti-thrombosis activity compared than that of aspirin. Our results suggest that the useful substances are produced from substrates and edible plant added during the fermentation, and the Korean traditional liquors could be developed as strong antibacterial and anti-thrombosis agents.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.3
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• pp.414-419
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• 2005

The current study was conducted to investigate the effects of dietary chitosan-alginate-Fe(II) complex (CAFC) supplementation on carcass and meat qualities of pig m. longissimus during chiller ageing. One hundred and twenty-two LYD (Landrace${\times}$Yorkshire${\times}$Duroc) pigs were sampled from an industrial population. Seventy-four pigs (32 gilts and 42 barrows) were administered 3 ml of dietary supplementation of CAFC per day from 25 to 70 days of age, while the remaining 48 pigs (20 gilts and 28 barrows) were fed the same commercial feeding regime without the supplementation. For assessing the dietary effects on pH, objective meat color, cooking loss, water-holding capacity (WHC), thiobarbituric acid reactive substances (TBARS), volatile basic nitrogen (VBN) and fatty acid composition during ageing, 20 barrows (10 of each treatment) were randomly sampled, and aged for 3, 7, 12, 16, 20 and 25 days in a $1^{\circ}C$ chiller. The results showed that CAFC-fed pigs required approximately 10 fewer feeding days than the control group. Furthermore, the treatment resulted in greatly higher carcass grade whereby the grade A was increased by approximately 35% and 7% for gilts and barrows, respectively. The treatment had no significant effect (p>0.05) on pH, meat color and WHC during ageing. On the other hand, the CAFC-fed pigs showed significantly (p<0.05) lower TBARS values from 20 days of storage. In addition, the sum of unsaturated fatty acids for the treated group was significantly (p<0.05) higher than that for the control group after the storage time. This implied that CAFC supplementation could reduce the formation of free radicals in fatty acids (i.e., lipid oxidation). The treatment also significantly (p<0.05) retarded VBN formation during ageing, indicating a significant reduction in protein degradation. However, as there was no difference in pH between the two groups, the result raised a possibility that antibacterial activity of the CAFC alone could cause reduction in the formation of TBARS and VBN. In this regard, although the treatment effectively slowed down the formation of TBARS and TBA during chiller ageing, it was not resolved whether that was associated with the direct effect of the antioxidant function of chitosan and/or alginate, or a consequence of their antibacterial functions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.2
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• pp.127-131
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• 2006

A study was carried out to produce antimicrobial peptides from zein treated with pretenses of six kinds. Among the pretenses of six kinds, zein hydrolysate treated with pepsin showed the highest antimicrobial activity. The zein hydrolysate with pepsin was fractionated with membrane filter (30,000 10,000 and 3,000 molecular weight cut-off) and antimicrobial activity was measured for each fractions. Antimicrobial activity appeared greatly in the fraction below 3,000 (molecular weight cut-off) . The fraction was re-fractionated by HPLC and substances of two peaks collected as a sample to measure antimicrobial activity. All of both peaks showed the antimicrobial activity but 1st peak exhibited a consistently higher antimicrobial activity than 2nd peak. Minimum inhibitory concentrations (MIC) were between 2.5 and 3.0 mg/mL. The peptide was heat-stable since antimicrobial activity was maintained after treated with heat for 20 min at $121^{\circ}C$. N-terminal amino acid sequence of peptide fractionated by HPLC was leucine, glutamic acid, proline, phenylalanine, aspartic acid and argenine. These results indicated that peptide isolated from zein hydrosate with pepsin can use as a natural preservative ingredient in food industry.