Kaş, Aykut
Utilization of hyperthermophilic microorganisms was suggested to improve reaction rates and insoluble pollutant degradation and minimize the risk of contamination in bioelectrochemical systems (BESs). So far only a small group of hyperthermophilic microorganisms were identified, which show the ability to donate electrons to solid electrodes in BESs and here we present a new culture that fits to this description. The iron reducing archaeal culture Geoglobus acetivorans, originally isolated from a hydrothermal structure, produced 1.53 ± 0.24 A/m2 peak current density in microbial electrolysis cells (MECs) operated at 80 °C. This current density value is 2.5 – 3 times higher than the previously reported electro-active behavior of closely related archaeal species of Ferroglobus placidus and Geoglobus ahangari with the exact reactor configuration. Maximum hydrogen production rate (QH2) was found as 0.57 ± 0.06 m3 H2/m3*d in the 5 mL Mini-MEC reactors fed with 10mM acetate. There was a visible biofilm formation on the anode and minimum 6 cycles of biohydrogen generation coupled with high current generation was observed. Upon longer operation of reactors, biofilm started to detach from the electrode surface and both hydrogen and current production were decreased. Cyclic voltammetry (CV) analysis produced a sigmoidal catalytic wave with a mid-point potential of −0.40 V (vs. Ag/AgCl). Direct electron transfer (DET) capability by G. acetivorans was shown with peak separation analysis, rapid current density recovery after media replacement and thick biofilm formation on the anode electrode. G. acetivorans was able to utilize complex organic waste in hyperthermophilic MECs, after initial biofilm formation with acetate.


Optimising clarification of carrot juice by bacterial crude pectinase
Uzuner, Sibel; Çekmecelioğlu, Deniz (2015-12-01)
This study was undertaken to search for potential use of crude bacterial pectinase enzyme produced from Bacillus subtilis grown on hazelnut shell hydrolysate in clarification of carrot juice and to optimize the enzyme load, pH and time using the Box-Behnken response surface methodology (RSM). The carrot juice was treated with the crude pectinase enzyme (5.60 U mL(-1)) at different concentrations (0.1-0.5%), pH (4-7), and time (2-6 h). The obtained enzyme was also compared with commercial fungal pectinase at...
Nitrite and nitrate removal efficiencies of soil aquifer treatment columns
Güngör, Kerem; Ünlü, Kahraman (2005-05-20)
Bench-scale soil column experiments were performed to examine the effects of soil type and infiltration conditions on the removal efficiencies of wastewater nitrites and nitrates during the biological ripening phase of soil aquifer treatment (SAT) columns. SAT was simulated in three 1-m-high soil columns packed with 3 different natural agricultural soils having sandy clay loam (SCL), loamy sand (LS) and sandy loam (SL) textures. All columns were equipped with tensiometers and soil-water sampling ports, and ...
Experimental investigation of particle filtration in compression resin transfer molding of advanced composites
Aydil Dalkıran, Tuğçe; Erdal Erdoğmuş, Merve; Department of Mechanical Engineering (2014)
With the inclusion of particle fillers in advanced continuous fiber reinforced composites, issues such as impregnation with increased viscosity of the injected resin leading to high process pressures and possible nonhomogeneous/directional composite properties due to filtering of filler particles necessitate the study of the relations between processing parameters and the resulting particle distributions. In this study, the particle-resin interaction during compression resin transfer molding (CRTM) and resi...
Intracellular alkaline proteases produced by thermoacidophiles: detection of protease heterogeneity by gelatin zymography and polymerase chain reaction (PCR)
Kocabıyık, Semra (2002-08-01)
In this study 24 thermoacidophilic archeal and bacterial strains isolated from hot-springs and hot-soils were screened for their ability to produce intracellular alkaline proteases. The protease activities of the strains, based on azocasein hydrolysis, showed a variation from 0.6 to 5.1 U. The cell extracts of three most potent producers were further examined and it was found that their proteases exhibited maximum activity at 60-70 degreesC and showed a pH Optimum over a range of pH 7.0-8.5. Gelatin zymogra...
Microwave assisted extraction of phenolic compounds from tomato and sour cherry pomaces
Şimşek, Meriç; Şümnü, Servet Gülüm; Department of Food Engineering (2010)
The objective of this study was to compare microwave assisted extraction (MAE) and conventional extraction methods for the extraction of total phenolic compounds (TPC) from tomato and sour cherry pomace. Antiradical efficiency (AE) of the extracts and also the concentration of phenolic compounds were determined. In MAE, the effects of microwave power (400 and 700 W), solvent type (water, ethanol and ethanol-water mixture at 1:1 v/v), extraction time (8-20 min) and solvent to solid ratio (10, 20 and 30 ml/g)...
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