Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 3Citation - Scopus: 3Comprehensive Analysis of Lutein and Loroxanthin in <i>scenedesmus Obliquus</I>: From Quantification To Isolation(Mdpi, 2024) Erdogan, Aysegul; Karatas, Ayca Busra; Demir, Dilan; Demirel, Zeliha; Akturk, Merve; Copur, Oyku; Conk-Dalay, MeltemCarotenoids are hydrophobic pigments produced exclusively by plants, fungi, and specific microbes. Microalgae are well suited for the production of valuable carotenoids due to their rapid growth, efficient isoprenoid production pathway, and ability to store these compounds within their cells. The possible markets for bio-products range from feed additives in aquaculture and agriculture to pharmaceutical uses. The production of carotenoids in microalgae is affected by several environmental conditions, which can be utilized to enhance productivity. The current study focused on optimizing the extraction parameters (time, temperature, and extraction number) to maximize the yield of carotenoids. Additionally, the impact of various nitrogen sources (ammonia, nitrate, nitrite, and urea) on the production of lutein and loroxanthin in Scenedesmus obliquus was examined. To isolate the carotenoids, 0.20 g of biomass was added to 0.20 g of CaCO3 and 10.0 mL of ethanol solution containing 0.01% (w/v) pyrogallol. Subsequently, the extraction was performed using an ultrasonic bath for a duration of 10 min at a temperature of 30 degrees C. This was followed by a four-hour saponification process using a 10% methanolic KOH solution. The concentration of lutein and loroxanthin was measured using HPLC-DAD at 446 nm, with a flow rate of 1.0 mL/min using a Waters YMC C30 Carotenoid column (4.6 x 250 mm, 5 mu m). The confirmation of carotenoids after their isolation using preparative chromatography was achieved using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with an atmospheric pressure chemical ionization (APCI) probe and UV-vis spectroscopy. In summary, S. obliquus shows significant promise for the large-scale extraction of lutein and loroxanthin. The findings of this study provide strong support for the application of this technology to other species.Article Citation - WoS: 12Citation - Scopus: 16Carotenoid Profile in Prochlorococcus Sp. and Enrichment of Lutein Using Different Nitrogen Sources(Springer Verlag, 2016) Erdoğan, Ayşegül; Demirel, Zeliha; Eroğlu, Ahmet Emin; Conk Dalay, MeltemVarious carotenoids of the cyanobacterium Prochlorococcus sp. are identified using chromatographic/spectroscopic techniques and quantified using HPLC-DAD. In the present study, β-apo-8′-carotenal was used as internal standard. Identification of carotenoids was carried out by comparing the retention time, absorption spectra, and mass spectra of unknown peaks with reference standards. All-trans-lutein was found to be the major carotenoid in this cyanobacterium, and, therefore, algal productivity and the potential for lutein accumulation were analyzed as a function of different nitrogen sources such as nitrate, nitrite, ammonia, and urea for cultivation. Among them, urea clearly led to the best lutein accumulation. According to the experimental evidence, lutein increased from 2.54 to 3.34 mg g−1 in the cyanobacteria when urea was used as the nitrogen source. © 2016, Springer Science+Business Media Dordrecht.Article Citation - WoS: 18Citation - Scopus: 22Fucoxanthin Content of Cylindrotheca Closterium and Its Oxidative Stress Mediated Enhancement(Central Fisheries Research Inst, 2016) Erdoğan, Ayşegül; Demirel, Zeliha; Conk Dalay, Meltem; Eroğlu, Ahmet EminProduction of fucoxanthin by diatoms has become an alternative research area due to their low cost, convenience and diversity. The fucoxanthin content of Cylindrotheca closterium and its enhancement by altering the cultivation conditions via oxidative stress were investigated in this study. For this purpose, the extraction parameters were optimized and the highest fucoxanthin concentration (6.58 mg g-1) was achieved within 15.0 minutes at 40 °C. Then, this yield reached to 10.15 mg g-1 in the presence of NaOCl and Fe2+. It is worth noting that, this is the first time that the effect of oxidative stress on fucoxanthin production in diatom has been studied according to our knowledge. Therefore, the results of this study and the discussion about the mechanisms can be a reference for the enrichment of fucoxanthin from other diatoms.Article Citation - WoS: 120Citation - Scopus: 127Equilibrium, Thermodynamic and Kinetic Studies for the Biosorption of Aqueous Lead(ii), Cadmium(ii) and Nickel(ii) Ions on Spirulina Platensis(Elsevier Ltd., 2008) Şeker, Ayşegül; Shahwan, Talal; Eroğlu, Ahmet Emin; Yılmaz, Sinan; Demirel, Zeliha; Conk Dalay, MeltemThe biosorption of lead(II), cadmium(II) and nickel(II) ions from aqueous solution by Spirulina platensis was studied as a function of time, concentration, temperature, repetitive reactivity, and ionic competition. The kinetic results obeyed well the pseudo second-order model. Freundlich, Dubinin Radushkevich and Temkin isotherm models were applied in describing the equilibrium partition of the ions. Freundlich isotherm was applied to describe the design of a single-stage batch sorption system. According to the thermodynamic parameters such as ΔG°, ΔH°and ΔS° calculated, the sorption process was endothermic and largely driven towards the products. Sorption activities in a three metal ion system were studied which indicated that there is a relative selectivity of the biosorbent towards Pb2+ ions. The measurements of the repetitive reusability of S. platensis indicated a large capacity towards the three metal ions.