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Öğe Effects of stirring and aeration rates on lipase production and growth of R. Delemar in the media containing glucose or molasses sucrose and pfc(2013) Açikel, Yeim Sa; Eran, Mehtap; Açikel, ÜnsalLipases (triacylglycerol hydrolases) are hydrolytic enzymes that can catalyze the hydrolysis of the ester bond of long-chain acylglycerols at the oil-water interface. The effects of stirring rate, aeration rate, and the amount of perfluorocarbon (PFC), as an oxygen carrier, in the nutrient media containing glucose or molasses sucrose as main carbon sources were investigated in a batch bioreactor. The maximum lipase activities in the media containing glucose or molasses sucrose as main C source were found to be 43.0 U/L and 102.83 U/L, respectively, at the stationary phase of growth (120th hour of fermentation), at 150 and 200 revolution per minute stirring rates, respectively. The effect of aeration rate on lipase activity was investigated in range of 1-4 vvm. The maximum lipase activities in the media containing glucose or molasses sucrose and 10% PFC were determined as 102.67 U/L, 171.20 U/L, respectively, at 2 vvm aeration rate.Öğe Optimization of acid phosphatase production and Zn(II) bioaccumulation by R. delemar using response surface method(Gazi Universitesi Muhendislik-Mimarlik, 2014) Ersan, Mehtap; Açikel, ÜnsalAcid phosphatase activity, Zn (II) bioaccumulation and growth of R. delemar were investigated as a function of pH, temperature and initial Zn(II) ion concentration. Experimental design was performed by response surface method (RSM) and Box-Behnken design. The proposed mathematical models were evaluated by analysis of variance (ANNOVA) statistically method. The best fit for acid phosphatase activity was obtained by linear model, the Zn(II) bioaccumulation and microorganism growth were characterized by quadratic equations. The optimum conditions for acid phosphatase activity, Zn(II) bioaccumulation and growth of R. delemar were found to be pH 5,03, 31,82 °C and an initial Zn(II) ion concentration of 30,15 mg/L. At these conditions the maksimum acid phosphatase activity Zn(II) bioaccumulation and microorganism concentration were determined as 794,098 mmol / L-min, 17,62 mg / L and 3,2038 g / L respectively. To test sensivity and validity of the optimum conditions the validation experiments were performed.Öğe Removal of tetraclycine by biocomposites synthesized with immobilization of Rhizopus delamar and Candida types(Gazi Universitesi Muhendislik-Mimarlik, 2019) Kip, Feray; Açikel, ÜnsalIn this study, tetracycline adsorption using the biocomposites prepared by the immobilization of chitosan polymer and Candida yeasts (Candida lipolytica, Candida membranaefaciens, Candida tropicalis, Candida utilis) and Rhizopus delemar fungus as a microorganism on chitosan was examined. In the used parameter ranges, temperature was determined as 25-550C, pH as 2-7, concentration as 10-100 mg / L, optimum pH value as 4.0 and optimum temperature as 250C, maximum capacity chitosan-Candida utilis biocomposite 1.179 mg / g as determined. The experimental equilibrium data were adjusted to the Freundlich isotherm model of chitosan and biocomposites and the kinetic data were adjusted to the pseudo-first-order kinetics model. Enthalpy, entropy and Gibbs free energy change of adsorption processes operating according to the thermodynamic parameters were determined to be exothermic and spontaneous. Chitosan-Candida utilis biocomposite for before and after adsorption FTIR, SEM analysis and characterization studies was realized. This study proved that the new PAN-Candida utilis biocomposite might emerge as alternatives for the removal of tetracycline. © 2019 Gazi Universitesi Muhendislik-Mimarlik. All rights reserved.Öğe Study of lipase enzym activity with Candida utilis yeast in different media condition(Gazi Universitesi Muhendislik-Mimarlik, 2015) Keklikcio?lu Çakmak, Neçe; Açikel, ÜnsalLipases (triacylglycerol hydrolases, EC 3.1.1.3) are hydrolytic enzymes that can catalyze the hydrolysis of the ester bond of long chain acylglycerols at the oil-water interface. In this study; the effects of initial pH, initial sucrose concentration, activators and inhibitors on Candida utilis yeast, lipase enzym are searched. It is qualified that the optimum pH value for growth rate of Candida utilis yeast and production of lipase enzym is 4. Molasses which is a remnant of sugar industry is used as a main carbon source in nutrient media that is prepared for experimental studies in which lipase enzym activity is worked out. In the media in which molasses is used as a main carbon source, it is observed that lipase enzym activity increases with the increase of initial sucrose concentration. Soybean oil, corn oil, olive oil, sunflower oil and canola oil are added to the nutrient media and when the additive effect of enzym activity is observed it is found out that the highest activity increase is 788, 5 U/L with the addition of 1, 25% soybean oil. The result is that; Cu(II) and Ni(II) metal ions in the fermantation media lower the lipase activity severly and besides, lowering effect of Ni(II) is much more than that of Cu(II).Öğe The effects of the composition of growth medium and fermentation conditions on the production of lipase by R. delemar(Scientific and Technical Research Council of Turkey, 2011) Açikel, Ünsal; Erşan, Mehtap; Sa? Açikel, YeşimLipases (triacylglycerol hydrolases) are hydrolytic enzymes that can catalyze the hydrolysis of the ester bond of long-chain acylglycerols at the oil-water interface. The present study investigated the effects of inducers, surface-active materials, activators, and inhibitors in the fermentation medium on lipase activity in Rhizopus delemar. In the presence of certain commercial oils and tributyrin as an inducer, lipase activity decreased in the order of sunflower oil > soybean oil > hazelnut oil > corn oil > tributyrin > olive oil. In addition, the effects of the stirring and aeration rates on lipase activity were investigated. To investigate the effect of surface-active materials on lipase activity 2 different surface-active materials, Tween-80 and rhamnolipid (biosurfactant), were used as comparatives with tributyrin. Maximum lipase activity was observed in the fermentation medium containing Tween-80 as both an inducer and surface-active material. The combined effects of molasses and sucrose on lipase production by R. delemar were also investigated. Lipase activity in the presence of activators decreased in the order of NaCl > KCl > CaCl2 > MgCl2 > gum arabic > EDTA, and maximum lipase activity of 964.55 U/L was obtained. The presence of heavy metal ions in the fermentation media severely inhibited lipase activity. Lipase activity in the presence of heavy metal ions decreased in the order of Fe2+ > Mn2+ > Co2+ > Ni2+. © TÜBİTAK.
