• Environmental Mutagens and Carcinogens
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• v.26 no.2
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• pp.48-52
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• 2006

Our investigation of the seaweed extracts, Ulva lactuca. The biological activities antioxidant, antimicrobial activity, antifungal and haemolytic activity of ethy-ether and ethyl-acetate extracts from the seaweed, Ulva lactuca were investigated. They were separately extracted using ethyl-ether and ethyl-acetate from dried samples at room temperature and freeze dried. Seaweed extracts were found to cause significant free radical scavenging effects on DPPH (1,1-diphenyl-2-picrylhydrazyl). Seaweed extracts had not significant haemolytic activity against human erythrocyte. This extracts exhibited in vitro broad-spectrum antimicrobial activity of gram-negative, gram-positive bacteria and without antifungal activity.

• Korean Journal of Medicinal Crop Science
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• v.17 no.5
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• pp.335-340
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• 2009

To evaluate the availability of Cudrania tricuspidata Bureau as a natural source of antimicrobials, the antimicrobial activity of methanol extracts of harvested parts was investigated using the paper disc diffusion method. The extracts from leaves and root bark had broad antimicrobial activity against various bacteria, including Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Streptococcus mutans, Listeria monocytogenes, Enterobacter aerogenes, Enterococcus faecalis, Salmonella choleraesuis subsp. choleraesuis, Vibrio vulnificus, and Pseudomonas aeruginosa and inhibited Bacillus cereus, Staphylococcus aureus, and Listeria monocytogenes, agents of food poisoning especially well. The extract from ripe fruit had a very high antimicrobial activity against Staphylococcus aureus with a 20.2 mm of clear zone at 50 mg/mL sample concentration. These results indicated that Cudrania tricuspidata could be used as new source for developing natural antimicrobial agents.

• Journal of Life Science
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• v.25 no.12
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• pp.1399-1407
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• 2015

Klebsiella pneumoniae is found in the normal flora of the skin, mouth, respiratory tract, urinary tract, and intestines in human. However, the stain is opportunistic pathogen, which is the causative agent of community acquired pneumonia. Corn silk has been known to be effective for antimicrobial activity against pathogenic bacteria, including K. pneumoniae, Staphylococcus aureus, Bacillus subtilis, Shigella spp., Salmonella spp., Escherichia coli, Pseudomonas aeruginosa, et al. In this study we focused on the antimicrobial properties of con silk water extract of K. penumoniae. K. pneumoniae isolates K. pneumoniae ATCC 13883 and broad-spectrum β-lactamase (BSBL), exteded-spectrum β-lactamase (ESBL), carbapenemase-producers. Antimicrobial susceptibilities were determined by the disk diffusion method. Searches for bla genes were performed by PCR amplication and direct sequencing. MacConkey agar plate medium was prepared using the corn silk extracts (50% or 100%) instead of distilled water for antimicrobial activity test. The microbial growth inhibitory potential of K. pneumoniae was determined by using the MacConkey agar plate spreading method, and the plate was incubated 18 hr at 37℃. Genes encoding β-lactamases including SHV-1 (n=8), SHV-2a (n=8), SHV-5 (n=2), SHV-11 (n=2), SHV-12 (n=18), TEM-1 (n=10), CTX-M-3 (n=2), CTX-M-14 (n=2), CTX-M-15 (n=1), GES-5 (n=5), KPC-2 (n=6), KPC-3 (n=4), and NDM-1 (n=2) were detected. The corn silk extract showed significantly antimicrobial activity against K. pneumoniae ATCC 13883, but BSBLs, ESBLs, and carbapenemase producers were not. Therefore, corn silk extract is thought to be able to assist in the prevention and rapid recovery of infectious disease caused by K. pneumoniae.

• BMB Reports
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• v.35 no.3
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• pp.291-296
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• 2002

Thanatin, a 21-residue peptide, is an inducible insect peptide with a broad range of activity against bacteria and fungi. It has a C-terminal disulfide loop, like the frog skin secretion antimicrobial peptides of the brevinin family. In this study, we tried to find the effect of a number of amino acids between the disulfide bond. Thanatin showed stronger antibacterial activity to Gram negative bacteria than other mutants, except Th1; whereas, the mutant peptides with deletion had higher activity to Gram positive bacteria than thanatin. An increase in the number of amino acid(s) using the alanine residue decreased the antibacterial activity in all of the bacteria. Th1 with deletion of threonine at position 15 ($Thr^{15}$) showed similar antibacterial activity against Gram-negative bacteria, but had higher activity against the Gram positive bacteria. In order to study the structure-function relationship, we measured liposome disruption by the peptides and CD spectra of the peptides. Th1 also showed the highest liposome leaking activity and α-helical propensity in the sodium dodecyl sulfate solution, compared with other peptides. Liposome disruption activity was closely correlated with the anti-Gram positive bacterial activity. All of the peptides showed no hemolytic activity. Th1 was considered to be useful as an antimicrobial peptide with broad spectrum without toxicity.

• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.366-371
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• 2010

Accompanying the rapid advance of nanotechnology, various nano-particles have shown promise as strong antimicrobial agents against a broad spectrum of microorganisms. These nanoparticles also have potential applications in medical devices, water treatments systems, environmental sensors and so on. However, with increasing concerns about the impact of engineered nanoparticles, many researchers are recently reporting the cytotoxicity of nanoparticles. In this review paper, we summarized the antimicrobial activities and mechanisms of various kinds of engineered nanoparticles to imprale understanding about these characteristics of nanoparticles.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.350-355
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• 2010

Among human antimicrobial peptides (hAMPs), DCD-1L has a broad spectrum of antimicrobial activity over a wide pH range and in high salt concentrations. It offers a promising alternative to conventional antibiotics. The 458-bp-long dermcidin cDNA was amplified by PCR using a human fetal cDNA library as a template. The 147-bp fragment of the MDCD-1L gene encoding an additional methionine residue was subcloned into the pTYB11 vector. Recombinant MDCD-1L was expressed as an intein fusion protein in E. coli, and then purified by affinity chromatography using chitin beads. A small peptide with a molecular mass of about 5 kDa was detected by tricine gel electrophoresis. The recombinant MDCD-1L peptide was purified from the gel and its amino acid sequence was determined by nanoLC-ESI-MS/MS analysis. The initiating amino acid, methionine, remained attached to the N-terminal region of recombinant MDCD-1L. Purified MDCD-1L showed antimicrobial activity against a Micrococcus luteus test strain.

• Preventive Nutrition and Food Science
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• v.4 no.1
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• pp.28-32
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• 1999

A novel antimicrbial peptide , named HFS-I, was isolated and characterized from the skin of the hagfish, Eptatretus bugeri. The decapeptide with a molecular mass of 1279.5 Da was purified to homogeneity using a gel-filtration column, ion-exchange and C18 reverse-phase high performance liquid chromatograpy . The complete amino acid sequence of HFS-I, which was determined by a combination of an automated amino acid sequencing and FAB-MS, was F-P-W-W-L-S-G-K-Y-P-NH2. Comparison of the amino acid sequence with those of other known antimicrobial peptides revealed that HFS-I was a novel antimicrobial peptide. HFS-I showed a weak antimicrobial activity in vitro aganinst a broad spectrum of microorganism without hemolytic acitivity.

• Fisheries and Aquatic Sciences
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• v.6 no.1
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• pp.27-33
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• 2003

A lactic acid bacterium showing antimicrobial activity against fish pathogen was isolated from gastrointestinal tract of flounder for the purpose of use as an aquaculture probiotics. From the analysis of morphological and physiological characteristics, the isolated strain was named as Lactococcus sp. HM58. Antimicrobial substance (AMS) from Lactococcus sp. HM58 showed strong growth inhibitory activity against Streptococcus sp., which is a fish pathogenic bacterium. AMS was presumed a proteinaceous compound with stability in heat and wide pH range from 2 to 10. It was started to produce in exponential growth phase and was not produced any more in stationary phase. It showed comparatively broad antimicrobial spectrum against most of gram positive bacteria used for this study. About $84\%$ of Lactococcus sp. HM58 was able to survive in the artificial gastric juice though it was low to the extent in the artificial bile juice. In the sensitivity test for various antibiotics, this strain was highly sensitive for doxycycline, erythromycin, amoxicillin clavu1anic acid and ampicillin.

• Food Science of Animal Resources
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• v.38 no.5
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• pp.1064-1079
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• 2018

In this study, the antimicrobial activity of a bacteriocin produced by Enterococcus faecalis KT11, isolated from traditional Kargı Tulum cheese, was determined, and bacteriocin KT11 was partially characterized. The results showed that bacteriocin KT11 was antagonistically effective against various Gram-positive and Gram-negative test bacteria, including vancomycin- and/or methicillin-resistant bacteria. The activity of bacteriocin KT11 was completely abolished after treatment with proteolytic enzymes (proteinase K, ${\alpha}$-chymotrypsin, protease and trypsin), which demonstrates the proteinaceous nature of this bacteriocin. Additionally, bacteriocin KT11 remained stable at pH values ranging from 2 to 11 and after autoclaving at $121^{\circ}C$ for 30 min. In addition, the activity of bacteriocin KT11 was stable after treatment with several surfactants (EDTA, SDS, Triton X-100, Tween 80 and urea) and organic solvents (chloroform, propanol, methanol, ethyl alcohol, acetone, hexane and ethyl ether). Cell-free supernatant of E. faecalis KT11 was subjected to ammonium sulfate precipitation and then desalted by using a 3.5-kDa cut-off dialysis membrane. The bacteriocin activity was determined to be 711 AU/mL in the dialysate. After tricine-SDS-PAGE analysis, one peptide band, which had a molecular weight of ~3.5 kDa, exhibited antimicrobial activity. Because the bacteriocin KT11, isolated from E. faecalis KT11, exhibits a broad antimicrobial spectrum, heat stability and stability over a wide pH range, this bacteriocin can be used as a potential bio-preservative in foods. Additionally, bacteriocin KT11 alone or in combination with conventional antibiotics may provide a therapeutic option for the treatment of multidrug-resistant clinical pathogens after further in vivo studies.

• Toxicological Research
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• v.29 no.2
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• pp.99-106
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• 2013

Clostridium difficile infection (CDI) has become a significant threat to public health. Although broad-spectrum antibiotic therapy is the primary treatment option for CDI, its use has evident limitations. Probiotics have been proved to be effective in the treatment of CDI and are a promising therapeutic option for CDI. In this study, 4 strains of lactic acid bacteria (LAB), namely, Lactobacillus rhamnosus (LR5), Lactococcuslactis (SL3), Bifidobacterium breve (BR3), and Bifidobacterium lactis (BL3) were evaluated for their anti-C. difficile activity. Co-culture incubation of C. difficile ($10^6$ and $10^{10}$ CFU/ml) with each strain of LAB indicated that SL3 possessed the highest antimicrobial activity over a 24-hr period. The cell-free supernatants of the 4 LAB strains exhibited $MIC_{50}$ values between 0.424 mg/ml (SL3) and 1.318 (BR3) mg/ml. These results may provide a basis for alternative therapies for the treatment of C. difficile-associated gut disorders.