İhsan Yaşa

Voltammetric determination of epinephrine by White rot fungi (Phanerochaete chrysosporium ME446) cells based microbial biosensor

The lyophilized biomass of White rot fungi (Phanerochaete chrysosporium ME446) was immobilized in gelatine using glutaraldehyde crosslinking agent on a Pt working electrode. The fungal cells retained their laccase activity under entrapped state. The immobilized cells were used as a source of laccase to develop amperometric epinephrine biosensor. The catalytic action of the laccase in the biosensor released an epinephrinequinone as a result of redox activity, thereby causing an increase in the current. The optimal working conditions of the biosensor were carried out at pH 4.5 (50 mM acetate buffer containing 100 mM K(3)Fe(CN)(6)), and 20°C. The sensor response was linear over a range of 5-100 μM epinephrine. The detection limit of the biosensor was found to be 1.04 μM. In the optimization and characterization studies of the microbial biosensor some parameters such as effect of fungi and gelatine amount, percentage of glutaraldehyde on the biosensor response and substrate specificity were carried out. In the application studies of the biosensor, sensitive determination of epinephrine in pharmaceutical ampules was investigated.

Production of laccase from Trametes trogii TEM H2: a newly isolated white‐rot fungus by air sampling

This work represents the first report of isolation of potential laccase producers by air sampling using media supplemented with 2,2‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonate) and guaiacol for laccase production and secretion indicators. Nine fungal isolates showed positive reactions with 2,2‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonate) and guaiacol. The isolate named TEM H2 exhibited the largest and intensive oxidation zones with 2,2‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonate) (85 mm) and guaiacol (66 mm) and therefore it was selected for detailed investigations. The strain was identified as Trametes trogii TEM H2 due to the morphological characteristics and the comparison of internal transcribed spacer ribosomal DNA gene sequences. The laccase production was screened in different liquid cultures. The best laccase production medium was determined as soluble starch yeast extract medium in which laccase production was reached to a maximum level (989.6 U l–1) on the 8th day of cultivation. Effects of different initial pH values on laccase production were tested. Optimum pH value for laccase production in soluble starch yeast extract medium was determined as pH 3.0 with 15425.0 U l–1laccase production at 12th day of cultivation. In addition, effects of eight inducers (veratryl alcohol, ferulic acid, 1‐Hydroxybenzotriazole, syringic acid, 2,2‐azinobis (3‐ethylbenzothiazoline‐6‐sulfonate), 1 mmol l–1 CuSO4, 3% ethanol, guaiacol) were examined. Only cultures with 2,5‐xylidine exhibited 1.9 fold increase in laccase activity reaching to 28890.0 U l–1. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Characterization and antimicrobial performance of nano silver coatings on leather materials

In this study, the characterization and the antimicrobial properties of nano silver (nAg) coating on leather were investigated. For this purpose, turbidity, viscosity and pH of nAg solutions prepared by the sol-gel method were measured. The formation of films from these solutions was characterized according to temperature by Differential Thermal Analysis-Thermogravimetry (DTA-TG) equipment. The surface morphology of treated leathers was observed using Scanning Electron Microscopy (SEM). The antimicrobial performance of nAg coatings on leather materials to the test microorganisms as Escherichia coli , Staphylococcus aureus , Candida albicans and Aspergillius niger was evaluated by the application of qualitative (Agar overlay method) and quantitative (percentage of microbial reduction) tests. According to qualitative test results it was found that 20 μg/cm 2 and higher concentrations of nAg on the leather samples were effective against all microorganisms tested. Moreover, quantitative test results showed that leather samples treated with 20 μg/cm 2 of nAg demonstrated the highest antibacterial activity against E. coli with 99.25% bacterium removal, whereas a 10 μg/cm 2 concentration of nAg on leather was enough to exhibit the excellent percentage reduction against S. aureus of 99.91%. The results are promising for the use of colloidal nano silver solution on lining leather as antimicrobial coating.

Flavonoid glycosides and methylinositol from Ebenus haussknechtii

Two flavonoid glycosides (compounds 1 and 3) of which one is reported for the first time and a methylinositol (compound 2) were isolated from the aerial parts of Ebenus haussknechtii (Leguminosae). The structures were established as quercetin-7-O-[α-L-rhamnopyranosyl(1 → 6)-β-D-galactopyranoside] (1), morin-3-O-[4-[5-(4-hydroxyphenyl)pentanoyl]-α-L-rhamnopyranosyl(1 → 6)-β-D-galactopyranosyl]-7-4′-di-O-methyleter (3), and methylinositol (2) on the basis of chemical and spectroscopic means. The antimicrobial activities of the extracts have also been examined.

Streptomyces sp. TEM 33 possesses high lipolytic activity in solid-state fermentation in comparison with submerged fermentation

ABSTRACT Solid-state fermentation (SSF) is a bioprocess that doesn’t need an excess of free water, and it offers potential benefits for microbial cultivation for bioprocesses and product development. In comparing the antibiotic production, few detailed reports could be found with lipolytic enzyme production by Streptomycetes in SSF. Taking this knowledge into consideration, we prefer to purify Actinomycetes species as a new source for lipase production. The lipase-producing strain Streptomyces sp. TEM 33 was isolated from soil and lipase production was managed by solid-state fermentation (SSF) in comparison with submerged fermentation (SmF). Bioprocess-affecting factors like initial moisture content, incubation time, and various carbon and nitrogen additives and the other enzymes secreted into the media were optimized. Lipase activity was measured as 1.74 ± 0.0005 U/g dry substrate (gds) by the p-nitrophenylpalmitate (pNPP) method on day 6 of fermentation with 71.43% final substrate moisture content. In order to understand the metabolic priority in SSF, cellulase and xylanase activity of Streptomyces sp. TEM33 was also measured. The microorganism degrades the wheat bran to its usable form by excreting cellulases and xylanases; then it secretes the lipase that is necessary for degrading the oil in the medium.

Apolar constituents of some biologically active Dianthus species from Western Anatolia

The apolar constituents of four Dianthus (Caryophyllaceae) species were determined by GC-MS. Palmitic, linoleic, and oleic acids were detected as dominant components in all species. D. elegans d’Urv. var. elegans had the highest antioxidant activity. All four species also showed considerable antimicrobial activity against S. epidermidis and C. albicans.

Synthesis and antimicrobial evaluation of sulfanilamide- and carbohydrate-derived 1,4-disubstitued-1,2,3-triazoles via click chemistry

Abstract4-Sulfanilamido substitued-1,2,3-triazoles conjugated with monosaccharides (8–17) including d-glucose, d-galactose, d-mannose, and d-fructose were synthesized in good yields from azidosugars with propargyl sulfanilamides using copper catalyst 1,3-dipolar cycloaddition reaction (CuAAC). The structures of new compounds were elucidated by liquid chromatography-mass spectrometry, infrared, one-dimensional- and two-dimensional-nuclear magnetic resonance techniques. All of the new compounds were tested in vitro against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella typhimurium, Klebsiella pneumoniae, Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans for their antibacterial and antifungal activities. Experimental results showed antimicrobial activity with minimum inhibitory concentrations values a ranging from 0.078 to 5.0 mg/mL against test microorganisms.

SCREENING AND SIMPLE PURIFICATION OF ALANINE DEHYDROGENASE IN BACILLUS STRAINS

ABSTRACT Alanine dehydrogenase (EC 1.4.1.1), in the presence of NAD+, catalyzes the reversible deamination of L-alanine. Screening of alanine dehydrogenase in bacillus strains was carried out to develop its utilization as an industrial and analytical catalyst. Eight bacillus strains were used, including Bacillus megaterium LA 199 which abundantly produces enzymes. Alanine dehydrogenase was purified simply from Bacillus megaterium LA 199 by heat treatment at pH 5.4, followed by DEAE-Sepharose CL-6B and Sepharose CL-2B chromotography. The enzyme consisted of six subunits with an identical molecular mass of 42.5 kDa. The Km were 1.17×10−2 mM for NADH and 5.12×10−2 mM for pyruvate.

Removal of textile dyes from aqueous solutions by biosorption on mushroom stump wastes

In this study, the biosorption capacity of Agaricus bisporus/white mushroom stump wastes was evaluated against basic (Basic Red 18), reactive (Levafix Braun E-RN) and acidic (Acid Red 111) dyes. The experiments were carried out with heat-dried and freezing-dried mushroom stump wastes (HDW and FDW). Freezing-dried mushroom stump wastes had laccase activity which showed decolourisation effect for reactive and basic dyes. FDW showed higher reactive dye biosorption capacity compared with HDW. On the other hand, acidic dye biosorption capacity of HDW proved to be considerably higher than that of FDW. Thermodynamic parameters of free energy, enthalpy and entropy obtained from biosorption reactive dye ranging from 293 to 323 K showed that the biosorption experiment was a spontaneous and endothermic process. In this study, the kinetics of the biosorption of reactive dye over mushroom stump wastes was also investigated. The investigation revealed that the process proceeds via pseudo-second-order kinetics. On the whole, this study has demonstrated that mushroom stump wastes are promising biosorbents for the decolourisation of waste water containing different kinds of dyes from textile industry.

MODIFICATION OF LYSOZYME WITH OLEOYL CHLORIDE FOR BROADENING THE ANTIMICROBIAL SPECIFICITY

Lysozyme from egg white was modified by covalent attachment of an oleyl group to the free amino groups of lysozyme. The aim of the chemical modification was to develop an effective antimicrobial lysozyme derivative against both gram-negative and gram-positive bacteria. Lysozyme with various degrees of modification was obtained by changing oleoyl chloride/lysozyme mass ratio. Lysozyme derivatives evidently exhibited an antimicrobial effect against Escherichia coli (ATCC 29998). The modification slightly changed the antimicrobial effect of lysozyme derivative against Staphylococcus aureus (ATCC 121002). Since there was a positive correlation between the modification degree and the antimicrobial effect against E. coli, it was concluded that the change in antimicrobial behavior was due to an increase in hydrophobicity of the enzyme molecule enabling it to penetrate through the bacterial membrane of E. coli. It was also shown that oleoyl chloride with an MIC value of 10 mg/mL was effective against both E. coli and S. aureus.