Yazar "Polat, Ece" seçeneğine göre listele
Listeleniyor 1 - 11 / 11
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Biotechnological product potential of Auxenochlorella protothecoides including biologically active compounds (BACs) under nitrogen stress conditions(Springer, 2023) Polat, Ece; Yavuztuerk-Guel, Bahar; Unver, Huelya; Altinbas, MahmutNitrogen stress can influence microalgae's growth characteristics, and microalgae grown in nitrogen-deficient conditions may produce higher or lower levels of biotechnological products as a result of metabolic changes. In photoautotrophic and heterotrophic cultures, nitrogen limitation has been proven effective in promoting lipid accumulation. In spite of this, no study has demonstrated a significant correlation between lipid content and other biotechnological products such as bioactive compounds (BACs). This research examines a strategy for lipid accumulation as well as the potential production of BACs with antibacterial properties in parallel with that strategy. This concept involved the treatment of the microalga Auxenochlorella protothecoides with low and high concentrations of ammonium (NH4+). This particular experiment reached a maximum lipid content of 59.5% using a 0.8 mM NH4+ concentration, resulting in the yellowing of the chlorophyll levels. Agar diffusion assays were conducted to determine the antibacterial activity of different extracts derived from the biomass when stressed with different levels of nitrogen. Algal extracts prepared by a variety of solvents showed different levels of antibacterial activity against representative strains of both gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria. Among the extracts tested, 500 mg/L ethyl acetate extract had the greatest antibacterial activity against Escherichia coli. In order to identify the components responsible for the extract's antibacterial activity, fatty acid methyl ester (FAME) analysis was performed. It has been suggested that the lipid fraction may be a valuable indicator of these activities since some lipid components are known to possess antimicrobial properties. In this regard, it was found that the amount of polyunsaturated fatty acid (PUFA) significantly decreased by 53.4% under the conditions with the highest antibacterial activity observed.Öğe Combined effect of phosphorus, magnesium, yeast extract on lipid productivity of Yarrowia lipolytica grown with molasses(Korean Institute Chemical Engineers, 2022) Polat, Ece; Yorucu, Gizem; Altinbas, MahmutInadequate global fossil fuel reserves have forced researchers to investigate alternative fuel sources, and oleaginous microorganisms have attracted attention with their potential. Since high lipid production yield is an important criterion for suitable fuel production, in this study an oleaginous yeast, Yarrowia lipolytica, was selected and the lipid and biomass productivity under molasses (M20) substrate and nutrient supplementation was investigated. The effect of phosphorus as dipotassium hydrogen phosphate (K2HPO4), magnesium as magnesium sulphate (MgSO4), and yeast extract supplementation to molasses (M20) were evaluated individually and in combination. In addition, two quadratic models, using Box-Wilson central composite design, were used to correlate the phosphorus, magnesium and yeast extract concentrations that would achieve the highest biomass and lipid productivity. The study has shown that molasses (M20) supplemented with 336 mg/L K2HPO4, 0.17 g/L MgSO4 and 4.54 g/L yeast extract had the highest biomass productivity (80.7 mg/L/hour) and the highest lipid productivity (28.3 mg/L/hour). These productivity results were 1.44-fold and 2.42-fold higher than those of yeast extract-peptone-dextrose (YPD) broth, respectively. With enhanced biomass and lipid productivity, Yarrowia lipolytica can thus be used effectively in the fermentation industry.Öğe Dual-mode cultivation of the mixed microalgal culture to induce lipid synthesis using anaerobic digestate as an ammonia source(Elsevier Sci Ltd, 2023) Polat, Ece; Altinbas, MahmutAnaerobic Digestate (AD) is a desirable and significant nutrient source for microalgal growth. It can be utilized as a part of the circular economy in the generation of high-value-added products. Dual-mode cultivation with AD as a substrate can be an efficient strategy to enhance the algal biomass and produce high-quality biodiesel. As dilution is required to prevent growth inhibition, in this study, growth optimization was initially carried out to figure out the best dilution ratio of AD, which corresponded to a wide range of 0 to 2,000 mg NH4-N/L concentrations. The Bold's basal medium with triple nitrate (3NBBM) that supplemented AD at 4 % dilution resulted in the highest biomass (2290 mg center dot L-1). After maintaining the highest biomass-producing condition, stressors such as sodium chloride (NaCl) and ferric chloride (FeCl3) have also been searched to increase lipid production. The lipid content has increased by 1.8-fold as a result of the stress (at 20 g center dot L-1 NaCl and 0.1 mg center dot L-1 FeCl3). At those stress conditions, the saturated fatty acid concentrations were around 33 % of the total fatty acid methyl esters (FAME). In addition, compliance with the biodiesel standards has also been ensured at 0.1 mg center dot L-1 FeCl3. The combination of AD with nutrients and salt stressors, like NaCl and FeCl3, within the concept of dual-mode cultivation, could be a viable strategy to produce sustainable, high-quality biodiesel with a high proportion of algal biomass and could be integrated into microalgae production facilities.Öğe Effect of different iron sources on sustainable microalgae-based biodiesel production using Auxenochlorella protothecoides(Pergamon-Elsevier Science Ltd, 2020) Polat, Ece; Yuksel, Ebubekir; Altinbas, MahmutIn this study, iron sources and their optimum concentrations for high-quality biodiesel production were determined on Auxenochlorella protothecoides microalgae. Three iron compounds-ferrous sulfate, ferric ethylenediaminetetraacetic acid (EDTA), and ferric chloride-were assessed regarding concentration, specific growth rate, lipid, and lipid quality in relation to fatty acid methyl ester (FAME) composition of microalgal biomass. Auxenochlorella protothecoides demonstrated high resistivity to high concentrations of iron species, still showing an ability to grow in the presence of iron concentrations as high as 21.60 mM. The highest saturated fatty acid (SFA), at 78.5% of FAME, was observed at 1.15 mM ferric chloride, and the highest biomass generation was observed at 1.08 mM ferrous sulfate. In addition, biodiesel and diesel fuel qualities were satisfactory with microalgae cultivated at 0.2 and 14.4 mM ferrous sulfate, 7.19 mM ferric EDTA, and 0.07-21.58 mM ferric chloride concentrations. The former may be more practical, since the use of this iron compound gives the desired result in a broader range. Overall, it can be inferred that high-quality lipid and biodiesel production can be obtained by changing the concentrations and sources of iron compounds. (C) 2020 Elsevier Ltd. All rights reserved.Öğe Enhanced biodiesel properties of Auxenochlorella sp. using chemical mutagenesis and Tralkoxydim(Taylor & Francis Inc, 2023) Polat, Ece; Altinbas, MahmutMutagenesis in microbial strains might result in robust strains with enhanced biofuel properties. Besides that, oleaginous microalgae, Auxenochlorella sp. with enhanced biomass and lipid content, can be a strong candidate for biodiesel production. In this context, a chemical mutagen called ethyl methane sulfonate (EMS) was screened at different concentrations. Considering that a lower survival rate can result in a higher mutation rate, an EMS concentration of 0.25M with 13 mins exposure time was selected as the optimum mutation condition. An acetyl-coenzyme A carboxylase (ACCase) inhibitor herbicide, tralkoxydim, was used as a selective environment to choose the mutant strains. Using an ACCase inhibitor herbicide would maintain a more desirable mutant strain that had the enhanced characteristics of biodiesel. Multi-scale comparisons between selected mutant strains and a wild strain revealed that by the time there was a remarkable decrease of 12.6% in the lipid content of the wild strain under the addition of Tralkoxydim (34.8%) compared to 39.8% in wild type, the lipid contents of the mutant strains remained higher. A remarkable increase by 1.50-fold and 1.33-fold in biodiesel fuel properties for Tralkoxydim-treated strains emphasizes that the ACCase synthesis pathway for lipid production is influenced by the stress factor that reaches the European biodiesel standards.Öğe Life cycle assessment of various algae technology: A case study(Nova Science Publishers, Inc., 2021) Koyunoğlu, Cemil; Polat, EceIt is known that environmental problems in our world and life are mostly caused by fossil fuel consumption. Issues such as global climate change, seasonal warming and narrowing of cooling periods have started to affect our daily life negatively in the world. This book chapter is intended to provide a methodical solution to these problems. In the recent COVID-19 outbreak, the spread of a virus infected by a bat species in a way that threatens human life also reveals that we do not exist in the world, that is, different living species from us are a determining factor in our lives. Like the famous physicist Einstein's word above. Life cycle assessment (LCA) became popular in the early nineties. This technique was initially considered as a direct marketing tool used during the environmental impact assessment of the whole production or the comparison of the two production stages. In the following periods, it was understood that the more effective results of this method were put forward not only as a marketing tool. Therefore, LCA application is important because it can be applied to all production methods. Especially in recent years, this method has started to be expressed as a critical method in environmental policies. The concept of integrated product policy is a prime example of this. Not only the European Union but also China and the United States are developing strategies that support this method as an important key. The attractiveness of this method is increasing day by day as the world's top 500 companies conduct sustainability reporting in their operations, especially in terms of LCA. In this study, firstly, we showed about fossil fuel power plants, and then we gave information about algae technology about the retention of flue gas in the atmosphere and lastly, the life cycle assessment for energy systems was evaluated to make flue gas to be less harmful to the environment. © 2021 by Nova Science Publishers, Inc. All rights reserved.Öğe Müsilaj Oluşumu ve Ekolojisi(2023) Polat, Ece; Ünver, Hülya; Altınbaş, MahmutMüsilaj oluşumu, çeşitli biyolojik ve hidrolojik etkileşimleri içeren çok karmaşık bir olgudur. Müsilaj oluşumuna elverişli koşullar oşinografik değişimlerle gözlenebilirken, ortamda bulunan bakteriyel ve fitoplanktona dayalı aktiviteler de müsilaj oluşumunda etkin rol oynar. 17. yüzyıldan beri farklı denizlerde ve ekosistemlerde gözlenmiş müsilajın, mikrobiyal yapısı ve şekli de farklıdır. Bu durumu, müsilaj oluşumunun çoğunlukla taksona özgü olması ve kalınlığının ile dokusunun ise çevresel faktörlerden etkilenmesi ile açıklamak mümkündür. Müsilaj araştırmalarında baskın tür olarak çoğunlukla fitoplankterler karşımıza çıkmaktadır. Özellikle, ortamdaki yüksek organik madde miktarı ve nutrient miktarları, fitoplankton oluşumu ve mikroçevre oluşumunu tetiklemektedir ve suyun sıcaklık, akışkanlık, türbidite gibi bazı özellikleri müsilaj üretimini artırıcı etki göstermektedir. Bu derlemede, öncelikle çözünmüş organik madde (ÇOM) ve mikrobiyal popülasyonun agregat oluşturarak nasıl müsilaja dönüştüğünden bahsedilmiştir. Sonrasında, mikrobiyal ekoloji incelemelerinde müsilajın yapısında karşılaşılmış canlı grupları anlatılmıştır. Müsilaj bölgelerinde gözlenen baskın türler, vaka bilgileri ile detaylı olarak anlatıldıktan sonra, müsilaj oluşumu sonucu yaşamı olumsuz etkilenen canlılardan bazı örnekler verilmiştir.Öğe Production and characterization of ionizing radiation shielding material from algal biomass(Pergamon-Elsevier Science Ltd, 2024) Polat, Ece; Gultekin, Batuhan; Canoglu, Mustafa Can; Altinbas, Mahmut; Ogul, HasanThis study employs several approaches to enhance environmental sustainability: First, algal biomass (with 52.5% protein content) was converted into value-added products. Second, residual algal biomass from protein extraction and pigment extraction and raw algal biomass were used to manufacture bioplastics. Third, radiation shielding performance of bioplastics has been investigated. As an alternative to plastics originated from petroleum-based raw materials, environmentally friendly bioplastics were derived from residual algae biomass after extraction. The gamma-ray radiation shielding properties of the produced bioplastic have been investigated using WinXCOM theoretical calculation and GEANT4 Monte Carlo (MC) simulation. Fast neutron shielding performance of the considered materials also evaluated with help of theoretical calculation and the same MC simulation. The produced bioplastics are similar to ones with commercially available PLA polymer. Sample 1 was found to be better gamma-ray attenuator while Sample 2 has the highest value of the effective neutron removal cross section. Additionally, the boron addition has resulted in lower water absorption capacity in the prepared samples. Using algae to produce more than one product as a raw material source will be an effective step toward sustainable life, and they could be an alternative gamma-ray shielding material to existing commercial polymers.Öğe Recovery of volatile fatty acids from anaerobic fermentation broth of baker's yeast industry effluent by liquid-liquid extraction(Elsevier Science Inc, 2025) Polat, Ece; Genc, Aysegul Nalan; Gungord, Fusun Seyma; Altinbas, MahmutAs metabolic intermediates, volatile fatty acids (VFAs) can be recovered by separation and purification and contribute to the economy. It was necessary, however, to investigate the optimization of liquid-liquid extraction (LLE) in this study because of the technical difficulties encountered during the recovery of VFAs. For this reason, the organic solvents diethyl ether, trioctylamine, and toluene were investigated as LLE solvents to extract VFAs from Baker's yeast industry effluent, which contains high levels of organic matter. An optimal pH value of 3 was determined by a pH scan performed between pH 2.5 and pH 7.5. Principal component analysis (PCA) was used to determine the effects of organic solvents and pH on extraction efficiency. The extraction efficiency was evaluated using the optimal pH and multi-stage extraction experiments. In a three-stage extraction, diethyl ether recovered 82% of the VFAs, making it a promising organic solvent for extracting VFAs from anaerobic fermentation broth. PCA revealed that an opposite correlation between VFA recovery and pH for each organic solvent. Based on the results of the cost analysis, it was determined that the costs of recovering VFAs were reduced by 90% per kilogram.Öğe Screening the Lipid Production Potential of Oleaginous Yeast Yarrowia lipolytica under Wood Hydrolysates(Mdpi, 2023) Unver, Huelya; Polat, Ece; Altinbas, MahmutSince Yarrowia lipolytica, an oily yeast, contains many valuable products as biomass, to increase its widespread use, it is very important to develop a sustainable production model. In this study, the production of high acid hydrolysate from sawdust biomass, which is produced in very high amounts in our environment, and the effect of these products on the growth efficiency of Yarrowia lipolytica were investigated. A preliminary statistical analysis was carried out to assess sugar production from sawdust by hydrolysis, which estimated 85% of total sugar recovery (TSR) using 96 g of sawdust, while TSR at the highest sawdust was as high as 79%. There was a higher loss in the recovery of C-5 sugars with acid and time. This study revealed that Y. lipolytica could grow with high biomass yields in varying hydrolysate concentrations, approaching yields achieved in synthetic glucose media. The maximum biomass obtained was 13 and 26 g in batch and airlift operations, respectively, using organic nutrients. Biomass and lipid yields from kinetic modeling provided a close approximation to the experimental yields performed on an airlift reactor. It was found that Y. lipolytica biomass cultivated on sawdust hydrolysates had significant lipid and protein compositions, as high as 29 and 38%, respectively.Öğe The Physiological Effects of Organic Solvents, Plant Growth Regulators, and Fungicide on Auxenochlorella protothecoides(Springer, 2023) Polat, Ece; Altinbas, MahmutThe cost of lipid production per biomass is an important factor for the expansion of the microalgal biorefinery industry. Some stressors and regulatory molecules, such as salicylic acid (SA), abscisic acid (ABA), indole-3-butyric acid (IBA), and carbendazim (CARB), can stimulate microalgal biomass and lipid quality, as well as improve their properties, by lowering unsaturated fatty acids, stimulating cell division and development, or causing oxidative stress. This study focused on identifying a microalgal growth condition that is compatible with enhanced lipid and biomass yields and high biodiesel quality while being highly resistant to stressors. Many carbon sources, such as glycerol (GLY), remain unclear as to how hormones and other stressors may stimulate growth under photoheterotrophic conditions, and GLY, also a regulator of fatty acid metabolism and hormone cross-talk, might enhance lipid accumulation under supplementation with phytohormones, fungicides, or even organic solvents. In addition, two organic solvents, three phytohormones, and one fungicide were evaluated, which are considered stressors to increase lipid productivity and the lipid quality of microalgae. Among the six stressors, 108 mu M SA and 2.5 mu M ABA combined with 8.4 g/L GLY resulted in the highest lipid productivity for Auxenochlorella protothecoides. In addition, supplementation with CARB concentrations of 260 mu M and 1040 mu M, ABA concentrations between 10 and 40 mu M, and an SA concentration of 360 mu M to GLY-modified Blue-Green (BG11) medium provided lipid productivity to satisfy biodiesel standards. As a general statement, organic solvents, plant hormones, and fungicides at various concentrations in combination with GLY can enhance microalgal biomass productivity and lipid quality by promoting microalgal-based biodiesel.
