Person: TOKSOY ÖNER, EBRU
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TOKSOY ÖNER
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Publication Metadata only Optimizing medium composition for TaqI endonuclease production by recombinant Escherichia coli cells using response surface methodology(ELSEVIER SCI LTD, 2005) TOKSOY ÖNER, EBRU; Nikerel, IE; Toksoy, E; Kirdar, B; Yildirim, RThe effect of medium composition on the TaqI endonuclease production, by recombinant Escherichia coli cells carrying a plasmid encoding TaqI endonuclease, was investigated using response surface methodology. The concentration of glucose, di-ammonium hydrogen phosphate, potassium di-hydrogen and magnesium sulphate in media were changed according to a central composite rotatable design consisting of 29 experiments and enzyme yields were determined. The results were fitted to a second order polynomial with an R-2 of 0.828. The model equation was then optimized using the Nelder-Mead simplex method to maximize enzyme yield within the experimental range studied. The optimum medium composition was found to be 6 g L-1 glucose, 1.5 g L-1 (NH4)(2)HPO4, 8 g L-1 KHPO4, and 0.8 g L-1 MgSO4 center dot 7H(2)O. The model prediction of 179 x 10(6) U g DCW-1 enzyme yield at optimum conditions was experimentally verified. This value is higher than any value obtained in the initial experiments as well as in the previously reported studies. The response surface methodology was found to be useful in improving the production of recombinant TaqI endonuclease in E. coli. (c) 2004 Elsevier Ltd. All rights reserved.Publication Metadata only Simultaneous modeling of enzyme production and biomass growth in recombinant Escherichia coli using artificial neural networks(ELSEVIER, 2008) TOKSOY ÖNER, EBRU; Gunay, M. Erdem; Nikerel, I. Emrah; Oner, Ebru Toksoy; Kirdar, Betuel; Yildirim, RamazanIn this work, the biomass growth and the TaqI endonuclease production by recombinant Esherichia coli were studied using artificial neural networks. The effects of the medium components on biomass growth and enzyme yield were modeled by various networks. After the most successful networks were statistically determined, they were used to extract additional knowledge such as the possible correlations between the biomass growth and the enzyme yield, and the relative significance of the medium components. It was found that the change of the biomass growth and the enzyme yield with the change of KH2PO4 concentration was strongly correlated with an R-value of -0.954. Some mild correlations were also observed for the other components. It was also found that the relative significances of the medium components were in the same order for both outputs: (NH4)(2)HPO4 Concentration was determined as the most important parameter followed by the glucose, KH2PO4 and MgSO4 concentrations. (C) 2008 Elsevier B.V. All rights reserved.Publication Metadata only Biological activities of bioceramic powders of various natural biological origins(ELSEVIER SCIENCE BV, 2009-09) TOKSOY ÖNER, EBRU; Tuyel, A. U.; Valerio, P.; Oner, E. Toksoy; Oktar, F. N.Publication Metadata only Genome-scale reconstruction of metabolic network for a halophilic extremophile, Chromohalobacter salexigens(ELSEVIER SCIENCE BV, 2009-09) TOKSOY ÖNER, EBRU; Ates, O.; Oner, E. Toksoy; Arga, K. Y.Publication Metadata only Effect of bioprocess conditions on growth and alkaline protease production by halotolerant Bacillus licheniformis BA17(ELSEVIER SCIENCE BV, 2007) TOKSOY ÖNER, EBRU; Nikerel, I. Emrah; Ates, Ozlem; Oner, Ebru ToksoyPublication Metadata only Comparison of industrial Saccharomyces cerevisiae strains for second generation bioethanol production(ELSEVIER SCIENCE BV, 2009-09) TOKSOY ÖNER, EBRU; Kasavi, C.; Finore, I.; Nicolaus, B.; Oner, E. Toksoy; Kirdar, B.; Oliver, S. G.Publication Metadata only Real imaging and size values of Saccharomyces cerevisiae cells with comparable contrast tuning to two environmental scanning electron microscopy modes(JOHN WILEY & SONS INC, 2007) TOKSOY ÖNER, EBRU; Misirli, Zulal; Oener, Ebru Toksoy; Kirdar, BetulThe combined application of electron microscopy (EM) is frequently used for the microstructural investigation of biological specimens and plays two important roles in the quantification and in gaining an improved understanding of biological phenomena by making use of the highest resolution capability provided by EM. The possibility of imaging wet specimens in their native states in the environmental scanning electron microscope (ESEM) at high resolution and large depth of focus in real time is discussed in this paper. It is demonstrated here that new features can be discovered by the elimination of even the least hazardous approaches in some preparation techniques, that destroy the samples. Since the analysis conditions may influence the morphology and the extreme surface sensitivity of living biological systems, the results obtained from the same cultured cell with two different ESEM modes (Lvac mode and wet mode) were compared. This offers new opportunities compared with ESEM-wet/Lvac-mode imaging, since wet-mode imaging involves a real contrast and Gives an indication of the changes in cell morphology and structure required for cell viability. In this study, wet-mode imaging was optimized using the unique ability of cell quantities for microcharacterization in situ giving very fine features of topological effects. Accordingly, the progress is reported by comparing the results of these two modes, which demonstrate interesting application details. In general, the functional comparisons have revealed that the fresh unprocessed Saccharomyces cerevisiae cells (ESEM-wet mode) were essentially unaltered with improved and minimal specimen preparation timescales, and the optimal cell viability degree was visualized and also measured quantitatively while the cell size remained unchanged with continuous images.Publication Metadata only Sequence variations within the genes related to hemostatic imbalance and their impact on coronary artery disease in Turkish population(PERGAMON-ELSEVIER SCIENCE LTD, 2007) TOKSOY ÖNER, EBRU; Taymaz, Hilal; Erarslan, Serpil; Oner, Ebru Toksoy; Alkan, Tijen; Agirbasli, Mehmet; Kirdar, BetulCoronary artery disease (CAD) is reported to be associated with some genetic risk factors. Since identification of genetic risk factors for CAD in different ethnic groups is important for the development of new intervention and prevention programs, we investigated the association between the R353Q and -323ins10 polymorphisms in Factor VII gene, C677T mutation in MTHFR, Factor V Leiden and PT G20210A mutations and CAD in Turkish population. The promoter region of the PAI-1 gene was also screened by SSCA (single-stranded conformation analysis) using specifically designed primers. 137 CAD patients with early onset documented by coronary angiography and 41 individuals who had no significant coronary stenosis by angiography as control group were screened for the identification of the polymorphisms. In conclusion, Factor V Leiden was found to be an independent genetic risk factor for CAD in Turkish population. Combined risk assessment indicated that the coexistence of two other inherited thrombophilia markers, namely MTHFR C677T and PT G20210A with Factor V Leiden may increase the risk of the development of the disease in this population. The results of the present study show that there is no statistically significant association between the two polymorphisms in Factor VII gene, MTHFR C677T polymorphism, PT G20210A polymorphism, 4G/5G polymorphism of PAI-1 and CAD in Turkish population. (c) 2006 Elsevier Ltd. All rights reserved.Publication Metadata only Molasses as fermentation substrate for microbial biopolymer production(ELSEVIER SCIENCE BV, 2009-09) TOKSOY ÖNER, EBRU; Kucukasik, F.; Yenigun, O.; Oner, E. ToksoyPublication Metadata only Modeling of batch fermentation kinetics for levan production by Halomonas spp.(ELSEVIER SCIENCE BV, 2009-09) TOKSOY ÖNER, EBRU; Kazak, H.; Arga, K. Y.; Oner, E. Toksoy