Bekir Salih

Multi-substrate growth kinetics of Pseudomonas putida for phenol removal

Abstract The biodegradation of phenol by a pure culture of Pseudomonas putida was investigated in a continuously fed stirred-tank reactor, under aerobic conditions. The dilution rate was varied between 0.0174 h−1 and 0.278 h−1, covering a wide range of dissolved oxygen and the inhibition region of phenol. Through non-linear analysis of the data, a dual-substrate growth kinetics, Haldane kinetics for phenol and Monod kinetics for oxygen, was derived with high correlation coefficients. Respective biokinetic parameters were evaluated as μm = 0.569 h−1, Kp = 18.539 mg/l, Ki = 99.374 mg/l, Ko = 0.048 mg/l, Yx/p = 0.521 g microorganism/g phenol and Yx/o = 0.338 g microorganism/g oxygen, being in good agreement with other studies in the literature. Maintenance factors for both phenol and oxygen were calculated for the first time for P. putida while the saturation coefficient for oxygen, Ko, was genuinely evaluated from the constructed model, not imported or adapted from other studies as reported in the literature. All pertinent biokinetic parameters for P. putida have been calculated from continuous system data, which are most appropriate for use in continuous bioprocess applications.

Protective effects of Turkish propolis on alcohol-induced serum lipid changes and liver injury in male rats

Abstract The chemical content of Turkish Castanea sativa propolis is investigated, along with its protective effect against alcohol-induced oxidative stress. The ethanol-propolis extract, at dose of 200 mg/kg body weight/day, was given, by gavage, to male rats for 15 days. At the end of the treatment, serum lipid levels, activities of liver enzymes and other biochemical parameters were measured. HDL level decreased and LDL level increased in the alcohol group, while HDL level increased and LDL level decreased in the alcohol+propolis group. There were decreases in cholesterol and triglyceride levels in the alcohol+propolis group. Also, there were decreases in ALP and AST enzyme activities, but LDH enzyme activity increased in the propolis treatment group compared to the alcohol group. No toxic effects of Turkish C. sativa propolis were found, while it caused an increase in HDL level and a decrease in LDL level. We suggest that these effects are protective against degenerative diseases and against alcohol-induced oxidative stress via free radicals.

Adsorption of heavy metal ions onto dithizone-anchored poly (EGDMA-HEMA) microbeads

The dithizone-anchored poly (EGDMA-HEMA) microbeads were prepared for the removal of heavy metal ions (i.e. cadmium, mercury, chromium and lead) from aqueous media containing different amounts of these ions (25-500 ppm) and at different pH values (2.0-8.0). The maximum adsorptions of heavy metal ions onto the dithizone-anchored microbeads from their solutions was 18.3, Cd(II); 43.1, Hg(II); 62.2, Cr(III) and 155.2 mg g(-1) for Pb(II). Competition between heavy metal ions (in the case of adsorption from mixture) yielded adsorption capacities of 9.7, Cd(II); 28.7, Hg(II); 17.6, Cr(III) and 38.3 mg g(-1) for Pb(II). The same affinity order was observed under non-competitive and competitive adsorption, i.e. Cr(III)>Pb(II)>Hg(II)>Cd(II). The adsorption of heavy metal ions increased with increasing pH and reached a plateaue value at around pH 5.0. Heavy metal ion adsorption from artificial wastewater was also studied. The adsorption capacities are 4.3, Cd(II); 13.2, Hg(II); 7.2, Cr(III) and 16.4 mg g(-1) for Pb(II). Desorption of heavy metal ions was achieved using 0.1 M HNO(3). The dithizone-anchored microbeads are suitable for repeated use (for more than five cycles) without noticeable loss of capacity.

Molecular switch based on a cucurbit[6]uril containing bistable [3]rotaxane.

A bistable CB6-based [3]rotaxane with two recognition sites has been prepared very efficiently in a high yield synthesis through CB6 catalyzed 1,3-dipolar cycloaddition; this rotaxane behaves as a reversible molecular switch and exhibits conformational changes caused by the movement of rings under base, acid and heat stimuli from one location to the other.

Catalase adsorption onto Cibacron Blue F3GA and fe(III)-derivatized poly(hydroxyethyl methacrylate) membranes and application to a continuous system

Poly(2-hydroxyethyl methacrylate) (poly(HEMA)) membranes were prepared by UV-initiated photopolymerization of HEMA in the presence of an initiator (a-a′-azobisisobutyronitrile, AIBN). An affinity dye, i.e. Cibacron Blue F3GA (CB) was incorporated covalently and then complexed with Fe(III) ions. The polyHEMA-CB and polyHEMA-CB-Fe(III) derivatized membranes were used in the adsorption of catalase (CAT). The enzyme-loading capability of the Fe(III)-containing membrane (23.6 μg/cm2) was greater than that of the poly(HEMA)-CB derivatized membrane (17.1 μg/cm2). The adsorption phenomena appeared to follow a typical Langmuir isotherm. The Km values for both immobilized catalases (poly(HEMA)-CB-CAT (22.4 mM) and poly(HEMA)-CB-Fe(III)-CAT (19.3 mM)) were higher than that of free enzyme (16.5 mM). Optimum operational temperature was 5°C higher than that of the free enzyme and was significantly broader. A similar observation was made for the optimum pH. Operational, thermal and storage stabilities were found to increase with immobilization, especially in the presence of Fe(III). It was observed that enzyme could be repeatedly adsorbed and desorbed without significant loss in adsorption capacity or enzyme activity.

Antibacterial Activity of Propolis versus Conventional Endodontic Disinfectants against Enterococcus faecalis in Infected Dentinal Tubules

INTRODUCTION The antibacterial activity against Enterococcus faecalis of 2 propolis samples was investigated in a dentin block model, and their effectiveness was compared with that of established endodontic disinfectants, chlorhexidine (CHX) and calcium hydroxide [Ca(OH)(2)]. METHODS Standardized dentin blocks were infected with E. faecalis ATCC 29212. The root canal space was filled with one of the ethanolic extracts of propolis (Artvin or Tekirdağ mix [TM]), CHX 2%, Ca(OH)(2), or ethanol or phosphate-buffered saline for control. Canal dentin was sampled after 1 or 7 days by using a standard-size bur. The dentinal shavings were vortexed vigorously in phosphate-buffered saline, and aliquots were cultured on tryptone soy agar plates. Colonies were counted after 2 days of incubation. Statistical significance was set to 5%. RESULTS All experimental agents significantly reduced the number of the cultivable bacteria. CHX was the most potent disinfectant at both times. Compared with the ethanol control, no significant reduction in the number of colonies was found for the propolis extracts at day 1; however, significant reduction was found at day 7. The 2 propolis samples were statistically similar to each other and to Ca(OH)(2), but the TM sample was also similar to CHX at day 7. This has been linked to the greater concentration of flavonoids, a group of antibacterially active compounds, in the TM sample as determined by gas chromatography-mass spectrometry analysis. CONCLUSIONS The antimicrobial activity of the propolis samples tested in this study was between Ca(OH)(2) and CHX. Both propolis samples were antimicrobially effective; however, their activity did not exceed CHX.

Alkali blue 6B-attached poly(EGDMA-HEMA) microbeads for removal of heavy-metal ions

Abstract In this study, we investigated a new sorbent system, i.e., Alkali Blue 6B-attached poly(EGDMA-HEMA) microbeads, for removal of heavy-metal ions from aqueous solutions. Poly(EGDMA-HEMA) microbeads were prepared by suspension copolymerization of ethyleneglycoldimethacrylate (EGDMA) and hydroxyethylmethacrylate (HEMA) by using poly-(vinylalcohol), benzoyl peroxide and toluene as the stabilizer, the initiator, and the diluent, respectively. Alkali Blue 6B molecules were then covalently attached to these microbeads. Microbeads (150–200 μm in diameter) with a swelling ratio of 55%, and carrying 23.6 μmol Alkali Blue 6B/g polymer were used in the adsorption/desorption studies. Adsorption rate and capacity of the microbeads for the selected metal ions, i.e., Cd(II), Cu(II), Zn(II) and Pb(II) were investigated in aqueous media containing different amounts of these ions (1–500 ppm) and at different pH values (1.5–7.5). Very high adsorption rates were observed at the beginning, and adsorption equilibria were then gradually achieved in about 5–90 min. The maximum adsorptions of metal ions onto the Alkali Blue 6B-attached microbeads were 5.5 mg/g for Cd(II), 2.3 mg/g for Cu(II), 41.4 mg/g for Zn(II), and 125 mg/g for Pb(II). However, when the metal ions competed (in the case of the adsorption from their mixture) the amounts of adsorption for Cd(II), Zn(II) and Pb(II) were quite close. Desorption of metal ions were studied by using 0.1 M HN03 (pH 1.0) for Cd(II), Cu(II), Zn(II) and Pb(II) ions. High desorption ratios (more than 90%) were achieved in all cases. Adsorption/desorption cycles showed the feasibility of repeated use of this novel sorbent system.

Biosynthesis and Characterization of Laccase Catalyzed Poly(Catechol)

Enzymatic polymerization of catechol was conducted batch-wise using laccase enzyme produced by the culture Trametes versicolor (ATCC 200801). The polymerization reaction was carried out in 1:1 (v/v) aqueous-acetone solution, buffered at pH 5.0 with sodium acetate (50 mM) in a sealed, temperature-controlled reactor at 25°C. The molecular weight of the produced polymer was determined with GPC. FT-IR, DSC, and TGA were employed to investigate the structure and thermal behavior of synthesized poly(catechol). It was found that catechol units were linked together with ether bonds and thermal stability of the catechol increased in the poly(catechol) polymeric structure effectively. The number average molecular weight of poly(catechol) was found as 813 ± 3 Da with a very narrow polydispersity value of 1.17 showing selective polymerization of catechol by the enzyme.

Cibacron Blue F3GA-attached polyvinylbutyral microbeads as novel magnetic sorbents for removal of Cu(II), Cd(II) and Pb(II) ions

Abstract Magnetic polyvinylbutyral based microbeads containing 12.4 μmol Cibacron Blue F3GA/g were used in the adsorption–desorption of some selected heavy metal ions, i.e., Cu(II), Cd(II) and Pb(II) from aqueous media containing different amounts of these ions (5–500 ppm) and at different pH values (2.0–8.0). Adsorption rates were high, and adsorption equilibria were reached in about 30 min. The maximum adsorptions of heavy metal ions onto the Cibacron Blue F3GA-attached affinity microbeads from their single solutions were 9.6 mg/g for Cu(II), 38.6 mg/g for Cd(II), 86.2 mg/g for Pb(II). When the heavy metal ions competed (in the case of the adsorption from their mixture) the amounts of adsorption were 6.5 mg/g for Cu(III), 20.3 mg/g for Cd(II) and 41.6 mg/g for Pb(II). Under non-competitive and competitive conditions the affinity order of ions was Pb(II)>Cd(II)>Cu(II). Desorption of heavy metal ions was achieved using 0.1 mol HNO3 in 30 min. It was observed that heavy metal ions could be repeatedly adsorbed and desorbed without significant loss in adsorption capacity.

Propolis from Turkey induces apoptosis through activating caspases in human breast carcinoma cell lines

Propolis is a sticky substance that is collected from plants by honeybees that has anti-mutagenic and anti-carcinogenic properties with biological and therapeutic effects. The target of this study was to investigate the anti-apoptotic effect of propolis extracts (PE) on the caspase pathway in the human breast cell line MCF-7 in culture. Seven different propolis extracts, numbered PE 1-7, produced in their natural ecological environment, were collected from the Hacettepe University Beytepe Campus area in Ankara, Turkey. Individual extracts at 0.5, 0.25, 0.125 and 0.063mg/ml were incubated with MCF-7 cells during 2 days culture. Cell growth and cytotoxicity were measured colorimetrically by MTT assay. Apoptotic cell death was determined by the TUNEL method (terminal deoxynucleotidyltransferase-biotin nick end-labelling) and caspase activity was investigated by immunocytochemistry using antibodies directed against caspase 6, caspase 8 and caspase 9. The results showed that the PE 5 and 6 extracts at 0.125mg/ml dilution induced apoptosis in association with increased number of TUNEL positive cells. MTT results showed that cultures exposed to the same extracts and at the same dilution experienced better cell growth compared to those cultures exposed to the other extracts. Immunpositivity for all caspases was detected after treatment with all the extracts and at all dilutions, with stronger immunoreactivity for caspase 6 than caspases 8 and 9. Caspase 6 labelling was especially strong in PE 5 and PE 6. We conclude that propolis may have anti-tumour effects by increasing apoptosis through the caspase pathway. Such propolis extracts may be important economically and allow development of a relatively inexpensive cancer treatment.