Hoşafcı, Ertan
The aim of this thesis study is to investigate factors affecting hydrogen (H2) and poly-hydroxybutyrate (PHB) production via photofermentation using two strains of Rhodobacter capsulatus species. To this purpose, three experimental designs were set up, namely Set 1, Set 2 and Set 3. In Set 1, various approaches in pretreatment of bacterial biomass were investigated. For R. capsulatus Wild Type (WT) strain, employment of different pretreatment methods did not make a significant difference, where an average of 29.6% of cell dry weight (cdw) PHB was observed. For mutant R. capsulatus YO3 strain, effect of drying was observed to be significant, with non-dried biomass samples yielding 40.1% of cdw average PHB compared to 28.2% of cdw for dried samples. It was concluded that YO3 should be adopted as the strain to be used in the following sets to be conducted and should not be subjected to drying. In Set 2, effect of increasing sodium (Na+) concentration was investigated as a potential stress condition, using two different substrate types, namely acetate and sucrose. As an indirect result of Na+ increase up to 4000 mgNa+/L, increasing pH was observed to be a significant stress condition. Maximum PHB accumulation was observed as 57.7 ± 5.2% and 3.3 ± 0.4% of cdw for acetate and sucrose, respectively. Maximum hydrogen productivities were observed as 0.58 ± 0.03 mmol/L·h and 0.73 ± 0.06 mmol/L·h, respectively for acetate and sucrose-containing reactors. In Set 3, effect of pH as a stress condition was investigated in high and low Na+ conditions. Maximum PHB accumulation was observed to be 57.5 ± 0.2% of cdw at 8.50 pH and 33.6 ± 2.0% of cdw at 7.70 pH for low and high Na+ conditions, respectively. Maximum hydrogen productivity was observed as 0.42 ± 0.01 mmol/L·h at pH 7.00.


Long-term biological hydrogen production by agar immobilized Rhodobacter capsulatus in a sequential batch photobioreactor
Elkahlout, Kamal; Alipour, Siamak; Eroglu, Inci; Gündüz, Ufuk; Yücel, Ayşe Meral (2017-04-01)
In this study, agar immobilization technique was employed for biological hydrogen production using Rhodobacter capsulatus DSM 1710 (wild type) and YO3 (hup-mutant) strains in sequential batch process. Different agar and glutamate concentrations were tested with defined nutrient medium. Agar concentration 4% (w/v) and 4 mM glutamate were selected for bacterial immobilization in terms of rate and longevity of hydrogen production. Acetate concentration was increased from 40 to 60-100 and 60 mM gave best result...
Kinetic analysis of photosynthetic growth, hydrogen production and dual substrate utilization by Rhodobacter capsulatus
Sevinc, Pelin; Gündüz, Ufuk; EROĞLU, İNCİ; Yucel, Meral (2012-11-01)
Rhodobacter capsulatus is purple non-sulfur (PNS) bacterium which can produce hydrogen and CO2 by utilizing volatile organic acids in presence of light under anaerobic conditions. Photofermentation by PNS bacteria is strongly affected by temperature and light intensity. In the present study we present the kinetic analysis of growth, hydrogen production, and dual consumption of acetic acid and lactic acid at different temperatures (20, 30 and 38 degrees C) and light intensities (1500, 2000, 3000, 4000 and 50...
Effect of light intensity, wavelength and illumination protocol on hydrogen production in photobioreactors
Uyar, Basar; EROĞLU, İNCİ; Yucel, Meral; Gündüz, Ufuk; Turker, Lemi (2007-12-01)
Rhodobacter sphaeroides O.U. 001 is a purple non-sulfur bacterium which evolves hydrogen from the breakdown of organic acids under illumination and anaerobic conditions. In this study, the effect of light intensity, light wavelength and illumination protocol on the growth and hydrogen production of R. sphaeroides O.U. 001 was investigated in gas-tight glass photobioreactors with defined medium. The results showed Also it was found that the rate of hydrogen production increased with increasing light intensit...
Comparison of Fenitrothion and Trifluralin Adsorption on Organo-Zeolites and Activated Carbon. Part II: Thermodynamic Parameters and the Suitability of the Kinetic Models of Pesticide Adsorption
LÜLE ŞENÖZ, Güzide Meltem; Atalay, Mustafa Ümit (Informa UK Limited, 2014-07-04)
The suitability of two kinetic models and the thermodynamic parameters of pesticide adsorption were investigated based on obtained data of previous studies. Kinetic evaluation indicated that the pesticides adsorption on adsorbents followed the pseudo-second-order model. Gibbs free energy (Delta G degrees), enthalpy (Delta H degrees), and entropy (Delta S degrees) were calculated for thermodynamic parameters by using linearized Arrhenius equation. The results indicated that the sorption process of fenitrothi...
Investigation of chemopreventive and apoptotic characteristics of turkish medicinal plant rheum ribes
Uyar, Pembegül; Çoruh, Nursen; İşcan, Mesude; Department of Biotechnology (2011)
Rheum species are medicinally important plants due to the presence of anthracene derivatives and in this study antioxidative, cytotoxic, apoptotic and chemopreventive characteristics of R. ribes extracts were evaluated. R. ribes shoot and root dry powder samples were prepared and extracted with ethyl acetate, ethanol and water. The extracts were revealed to be a potential scavenger of DPPH radicals and the chemical composition of the extracts was quantified by colorimetric determination of total phenol (GAE...
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