• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.651-661
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• 2019

Targeting the pathogen viability using drugs is associated with development of drug resistance due to selective pressure. Hence, there is an increased interest in developing agents that target bacterial virulence. In this study, the inhibitory effect of ciclopirox, an antifungal agent with iron chelation potential, on the microbial virulence factors was evaluated in 26 clinical MDR Pseudomonas aeruginosa isolates collected from Alexandria Main University Hospital, a tertiary hospital in Egypt. Treatment with 9 ㎍/ml ciclopirox inhibited the hemolytic activity in 70% isolates, reduced pyocyanin production, decreased protease secretion in 46% isolates, lowered twitching and swarming motility, and decreased biofilm formation by 1.5- to 4.5-fold. The quantitative real-time PCR analysis revealed that treatment with ciclopirox downregulated the expression levels of alkaline protease (aprA) and pyocyanin (phzA1). Ciclopirox is used to treat hematological malignancies and the systemic administration of ciclopirox is reported to have adequate oral absorption with a satisfactory drug safety profile. It is important to calculate the appropriate clinical dose and therapeutic index to reposition ciclopirox from a topical antifungal agent to a promising virulence-modifying agent agent against P. aeruginosa, a problematic Gram-negative pathogen.

• Korean Journal of Veterinary Research
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• v.57 no.3
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• pp.201-204
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• 2017

A Gram-negative, catalase- and oxidase-positive, coccus-shaped bacterium was isolated from a rabbit with keratoconjunctivitis. Colonies of the isolate were round, smooth, and exhibited hemolytic activity on 5% sheep blood agar. Scanning electron microscopy revealed 0.4 to $0.5{\mu}m$ diameter oval cocci. Partial 16S rRNA gene (1446 bp) sequence analysis demonstrated the isolate had significant homology with the Moraxella cuniculi CCUG2154 strain isolated from a rabbit in Germany in 1973. Our isolate was designated as APQAB1701. Antibiotic susceptibility tests demonstrated that APQAB1701 was sensitive to 24 antibiotics; 3 of the antibiotics (nalidixic acid, spectinomycin, and colistin) had minimal inhibitory concentrations ${\geq}32{\mu}g/mL$ against the isolate.

• Journal of Life Science
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• v.8 no.5
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• pp.598-603
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• 1998

A marine microbe, Vibrio anguillarum was isolated from fish and studied for its concerning pathogenic substance of hemolysin. Purification of hemolysin was achieved by the procedure of ammonium sulfate precipitation from cul-ture filtrate, DEAE-cellulose chromatography, and G-200 gel filtration with 36 fold of purification and 2.3% yield. The molecular weight of the purified hemolysin was 38,000 dalton by SDS-PAGE. The purified hemolysin was stable at pH 6-9, below 45$^{\circ}C$, and up to 1% of NaCl, respectively. $Ca^{2+}, Cu^{2+}, Zn^{2+}, Fe^{2+}$ inhibited the hemolytic activity whereas EDTA and $Mg^{2+}$ did not.

• Mycobiology
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• v.36 no.1
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• pp.50-54
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• 2008

This study examined the chemical composition of A. blasiliensis and the chemical structural properties of an immuno-stimulating polysaccharide. The amino acids, free sugars, and organic acids by HPLC and fatty acids by GC were analyzed. The immuno-stimulating substance from A. blasiliensis was extracted with hot water and purified by ethanol precipitation. It underwent ion exchange chromatography on DEAE-cellulose and gel filtration on Toyopearl HW 65F. Through GP-HPLC, the substance was found to be homogeneous. Its chemical structure was determined by $^{13}C-NMR$. Fatty acids, organic acids, and sugar alcohol composition consisted exclusively of linoleic acid, fumaric acid and mannitol, respectively. The amino acids were mainly glutamic acid, glycine, and arginine. By $^{13}C-NMR$ analysis, the immuno-stimulating substance was identified as ${\beta}-(1{\rightarrow}3)\;(1{\rightarrow}6)$-glucan, composed of a backbone with $(1{\rightarrow}3)$-linked D-glucopyranosyl residues branching a $(1{\rightarrow}6)$-linked D-glucopyranosyl residue. The ${\beta}$-glucan from A. blasiliensis showed pronounced immuno-stimulating activity on the antibody-production ability of B-lymphocytes by the hemolytic suspension assay. In these results, A. blasiliensis was estimated to have potent pharmacological properties and potential nutritional values.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.312-315
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• 2014

So as to evaluate its use an immune stimulator in humans, the toxicity and action against immune cells by an anti-yeast substance (AYS), a bacterial proteoglycan, were investigated. The AYS did not possess hemolytic activity with human red blood cells (hRBC). Nor did it exhibit cytotoxicity against human peripheral blood mononuclear cells (hPBMC). In addition, the AYS did not induce hPBMC proliferation, but it did agglutinate hPBMCs in vitro. Moreover, hPBMC induced inflammatory cytokines such as IL-6, IL-5, IFN-${\gamma}$ and TNF-${\alpha}$ with the AYS during culture. Compared with alum, the AYS as an adjuvant has an increased antibody production rate against bovine serum albumin (BSA) in mice.

• BMB Reports
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• v.40 no.1
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• pp.113-118
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• 2007

Tolaasin, a pore-forming peptide toxin, is produced by Pseudomonas tolaasii and causes brown blotch disease of the cultivated mushrooms. P. tolaasii 6264 was isolated from the oyster mushroom damaged by the disease in Korean. In order to isolate tolaasin molecules, the supernatant of bacterial culture was harvested at the stationary phase of growth. Tolaasin was prepared by ammonium sulfate precipitation and three steps of chromatograpies, including a gel permeation and two ion exchange chromatographies. Specific hemolytic activity of tolaasin was increased from 1.7 to 162.0 HU $mg^{-1}$ protein, a 98-fold increase, and the purification yield was 16.3%. Tolaasin preparation obtained at each purification step was analyzed by HPLC and SDS-PAGE. Two major peptides were detected from all chromatographic preparations. Their molecular masses were analyzed by MALDI-TOF mass spectrometry and they were identified as tolaasin I and tolaasin II. These results demonstrate that the method used in this study is simple, time-saving, and successful for the preparation of tolaasin.

• Journal of Microbiology and Biotechnology
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• v.28 no.12
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• pp.2064-2070
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• 2018

Pseudomonas tolaasii 6264 is a representative strain that causes bacterial blotch disease on the cultivated oyster mushroom, Pleurotus ostreatus. Bacteriophages are able to sterilize the pathogenic P. tolaasii strains, and therefore, they can be applied in creating disease-free mushroom cultivation farms, through a method known as "phage therapy". For successful phage therapy, the characterization of phage-resistant strains is necessary, since they are frequently induced from the original pathogenic bacteria in the presence of phages. When 10 different phages were incubated with P. tolaasii 6264, their corresponding phage-resistant strains were obtained. In this study, changes in pathogenic, genetic, and biochemical characteristics as well as the acquired phage resistance of these strains were investigated. In the phylogenetic analyses, all phage-resistant strains were identical to the original parent strain based on the sequence comparison of 16S rRNA genes. When various phage-resistant strains were examined by three different methods, pitting test, white line test, and hemolytic activity, they were divided into three groups: strains showing all positive results in three tests, two positive in the first two tests, and all negative. Nevertheless, all phage-resistant strains showed that their pathogenic activities were reduced or completely lost.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.168-174
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• 2011

In order to develop safe and economic novel antifungal agents, we prepared 73 methanol extracts from medicinal and edible herbs and examined their 365 solvent fractions using n-hexane, methylene chloride, ethylacetate, butanol and water residue based on the sequential organic solvent fraction method. When using the various fractions in the screening step for antifungal activity, we discovered ethylacetate fraction of Morus alba L., methylene chloride fraction of Pimpinella brachycarpa (MCPB), and n-hexane fraction of Salvia miltiorrhiza Bunge, which all have activities in methanol extracts, as potential sources of antifungal agents. Amongst these, the antifungal activity of P. brachycarpa has not to date been reported on. In addition, the mycelial growth inhibition and spore germination inhibition activities of MCPB against A. niger were confirmed by disc-diffusion assay in a 10 day culture. The MIC and MFC of MCPB were determined as 0.25 and 0.5 mg/ml, respectively. The MCPB has no hemolytic activity against human RBC at 0.5 mg/ml and glycoside-flavonoids are theorized to be active constituents. These results suggest that MCPB has a prominent antifungal activity and that the application of sequential organic solvent fractions, instead of simple natural product extracts, is useful in the screening process of novel bioactive substances.

• Applied Biological Chemistry
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• v.35 no.1
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• pp.42-50
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• 1992

We conducted screening on Chinese medicinal herbs to examine their anti-complementary activity by hemolytic complementary assay $(TCH_{50})$. Among 55 kinds of herbs, several herbs showed relatively potent anti-complementary activity which decreased $TCH_{50}$, more than 70% in comparison with control. Then, hot water extracts of the following herbs, Curcuma aromatica, Areca catechu, Gleditsiae spina, Euonymus alata, Acanthopanax senticous. Lonicera japonica, Aconitum carmichaeli, Curcuma zedoaria and Cinnamoum cassia, which were shown relatively potent anti-complementary activity were partially purified and analyzed their chemical properties. These activities were resistant to digestion with pronase but decreased by treatment with $NaIO_4$. These results may indicate that the complement activating ability in their herbs is due to polysaccharide. Furthermore, the anti-complementary activity of Areca catechu which was showed the most potent activity, was reduced partially in the absence of the $Ca^{++}\;ion$. After incubation of the normal human serum with partially purified polysaccharide of A. catechu in the absence of $Ca^{++}\;ion$, a cleavage of C3 in the serum was found to have occurred through immunoelectrophoresis using rabbit anti-human C3 serum. These results indicate that the mode of complement activation by polysaccharide of A. catechu is via both the alternative and classical pathway.

• Applied Biological Chemistry
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• v.50 no.4
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• pp.257-261
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• 2007

Tolaasin, a peptide toxin produced by Pseudomonas tolaasii, causes a serious disease on the cultivated mushrooms, known as brown blotch disease. Hemolysis using red blood cells was designed to measure the cytotoxicity of tolaasin molecules. Since tolaasin has two amine groups near the C-terminus, its membrane binding will be dependent on the ionic states of the amine groups. When the tolaasin peptide was titrated, its titration curve indicated the presence of titratable amine(s) at pH ranges from 7.0 to 9.6. When the pH-dependence of tolaasin-induced hemolysis was measured at various pHs, hemolysis was more efficient at alkaline pHs. In order to measure the membrane binding activity of tolaasin at different pHs, RBCs were incubated with tolaasin molecules for short time periods and washed out with fresh buffer. Because of the tolaasin binding during the preincubation period, fast hemolyses were observed at pH 8 or higher. These results imply that non-charged or less positively charged states of tolaasin molecules easily bind to membrane and show high hemolytic activity.