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Öğe Bioremediation and Decolorization of Textile Dyes by White Rot Fungi and Laccase Enzymes(Springer International Publishing Ag, 2018) Yesilada, Ozfer; Birhanli, Emre; Geckil, Hikmet[Abstract Not Available]Öğe Chitosan/polypropylene glycol hydrogel composite film designed with TiO2 nanoparticles: A promising scaffold of biomedical applications(Elsevier, 2020) Ulu, Ahmet; Birhanli, Emre; Koytepe, Suleyman; Ates, BurhanThe present study explores the preparation and characterization of chitosan/poly (propylene glycol)/titanium dioxide (CH/PPG/TiO2) composite hydrogels in view of their developing applications such as antimicrobial packaging, wound dressing and antibacterial materials. The prepared CH/PPG/TiO2 films were comprehensively characterized by several methods. The size distribution showed the average size of the TiO2 nanoparticles (NPs) was about 40 nm. Additionally, other properties including swelling ratio, water retention, water contact angle, porosity, water uptake, in vitro enzymatic degradation, water vapor transmission rate, in vitro biomineralization studies, and mechanical tests were evaluated in detailed. Besides these characterizations, the antimicrobial activity of CH/PPG/TiO2 composite film against Staphylococcus aureus, Escherichia coli, and Candida lipolytica was evaluated by using disc diffusion method. Based on the obtained results, the CH/PPG/TiO2 composite hydrogels showed enhanced water vapor permeability, porosity, water retention, and swelling ratio. An improvement was observed in the examined mechanical and thermal properties with the addition of TiO2 NPs. The tensile strength and elongation at break values of CH/PPG/TiO2 were 3.0 MPa and 31%, respectively. Most importantly, the CH/PPG/TiO2 composite hydrogels showed strong antimicrobial properties. Finally, the developed composite scaffold prepared in this study may possess potentially useful in biomedical applications. (C) 2020 Elsevier B.V. All rights reserved.Öğe Comparison of indigo carmine decolorization by Pseudomonas aeruginosa and crude laccase enzyme from Funalia trogii(Tubitak Scientific & Technological Research Council Turkey, 2019) Boran, Filiz; Birhanli, Emre; Yesilada, Ozier; Ozbey, ElifThe effects of incubation time, temperature, initial pH, and dye concentration on the indigo carmine decolorization activity of Pseudomonas aeruginosa ATCC 10145 and some factors on the decolorization potential of crude laccase enzyme obtained from Funalia trogii ATCC 200800 were comparatively investigated. This bacterium showed effective decolorization activity at all agitation and temperature values. Indigo carmine was greatly decolorized by P. aeruginosa at all pH values except pH 10. A decrease in decolorization activity occurred with increasing dye concentration, but this bacterium effectively decolorized the dye within 24 h. The decolorization process was through microbial metabolism, not biosorption. No decolorization or laccase activity could be obtained by the cell-free intracellular extract or culture filtrate of this bacterium. On the other hand, crude laccase effectively decolorized indigo carmine under highly acidic conditions, especially at pH 3.0 as 57% in 300 seconds. This activity decreased progressively due to the increase in pH values. In a short incubation period and at high temperature values, the crude laccase enzyme removed the color of the dye at 50 degrees C (56%), 60 degrees C (45%), and 70 degrees C (38%). These data are important for improving methods for decolorization of textile dyes used at high temperatures in various industrial applications.Öğe Design of laccase-metal-organic framework hybrid constructs for biocatalytic removal of textile dyes(Pergamon-Elsevier Science Ltd, 2022) Birhanli, Emre; Noma, Samir Abbas Ali; Boran, Filiz; Ulu, Ahmet; Yesilada, Ozfer; Ates, BurhanThis study aims to present a simple and effective carrier matrix to immobilize laccase as opposed to complex and tedious immobilization processes and also to use it in the removal of textile dyes. For this purpose, Cobalt (Co) and Copper (Cu) based metal-organic frameworks (MOFs) were prepared and laccase was immobilized on two different MOFs via encapsulation. The characterization outcomes showed that laccase was well immobilized into MOF supports. Optimum pH and temperature were found for Lac/Co-MOF (pH 4.5 at 50 degrees C) and Lac/Cu-MOF (pH 5.0 at 50 degrees C). The Km (0.03 mM) and Vmax (97.4 mu mol/min) values of Lac/Cu-MOF were lower than those of Lac/Co-MOF (Km = 0.13 mM, Vmax = 230.7 mu mol/min). The immobilized laccases showed good reusability as well as improved resistance to temperature denaturation and high storage stability. For instance, the Lac/Co-MOF and Lac/Cu-MOF retained more than 58% activity after 4 weeks of storage at room temperature. Meanwhile, Lac/Co-MOF and Lac/Cu-MOF maintained 56.5% and 55.8% of their initial activity, respectively, after 12 reuse cycles. Moreover, thermal deactivation kinetic studies of immobilized laccases displayed lower k value, higher t1/2, and enhancement of thermodynamic parameters, which means better thermostability. Finally, the decolorization activities for the Lac/Co-MOF were 78% and 61% at the 5th cycle for Reactive Blue 171 andÖğe The effect of various inducers and their combinations with copper on laccase production of Trametes versicolor pellets in a repeated-batch process(Tubıtak scıentıfıc & technıcal research councıl turkey, ataturk bulvarı no 221, kavaklıdere, ankara, 00000, turke, 2017) Birhanli, Emre; Yesilada, OzferThe aim of this study was to increase laccase production in Trametes versicolor ATCC 200801 pellets by using various inducers and their combinations under repeated-batch conditions. Because copper is an effective inducer for laccase production, the effect of Cu on laccase production in this strain was tested first. The optimal Cu concentration for the highest laccase production was 0.5 mM. Following this preliminary study, the effect of other inducers [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), syringaldazine, guaiacol, and 2,5-xylidine] on laccase production was determined. Copper was determined to be the most efficient inducer among the inducers used. Therefore, the synergistic effect of each inducer with Cu on laccase production in this strain was investigated. While the maximum laccase activity was 0.60 U/mL in stock basal medium (SBM) alone, the highest enzyme activities detected were 4.76 and 2.87 U/mL in SBM + 0.05 mM ABTS and SBM + 1 mM 2,5-xylidine, respectively. Maximum laccase activities obtained from the combination of the inducers were 33.61 and 26.49 U/mL in SBM + 0.5 mM Cu + 0.5 mM 2,5-xylidine and SBM + 0.5 mM Cu + 0.05 mM ABTS, respectively. These were the most efficient combinations for laccase production.Öğe Enhanced production of laccase in repeated-batch cultures of Funalia trogii and Trametes versicolor(Elsevier Science Bv, 2010) Birhanli, Emre; Yesilada, OzferThe biotechnologically important enzyme laccase (benzenediol: oxygen oxidoreductase: EC 1.10.3.2) is secreted by white rot fungi. However, these organisms produce insufficient amount of laccase for use in various biotechnological areas. The main aim of this study is to enhance the laccase production in the repeated-batch cultures of Funalia trogii ATCC 200800 and Trametes versicolor ATCC 200801 isolated in Turkey. In this study, laccase production in the repeated-batch cultures of F. trogii and T. versicolor pre-grown pellets were investigated under various conditions. Retention time, temperature, agitation, pH and the amount of pellets were found to be important for laccase production during repeated-batch studies. The culture filtrate showed one protein band. Zymogram gel also showed only one band of activity. The enzyme remained fully active when frozen for 300 clays. The immobilized fungi were also able to produce high amounts of laccase during reuse. It is possible to obtain high laccase amounts with free and immobilized repeated-batch cultures under the most appropriate culture conditions determined. Considering the various biotechnological applications of laccase, an enhancement in laccase production through the selection of appropriate culture conditions could facilitate the development of more economical and environmentally friendly processes. (C) 2010 Elsevier B.V. All rights reserved.Öğe The evaluation of pre-grown mycelial pellets in decolorization of textile dyes during repeated batch process(Springer, 2010) Yesilada, Ozfer; Yildirim, Seval Cing; Birhanli, Emre; Apohan, Elif; Asma, Dilek; Kuru, FilizThis study was undertaken for the possibility of application of pre-grown pellets for biotechnological treatment of dyes and textile industry waste waters. Mycelial pellets of five different white rot fungi were tested for their dye decolorization activity. The pellets of Funalia trogii, Phanerochaete chrysosporium and Trametes versicolor were determined as the most effective ones. The decolorization ability of viable pellets was compared with the decolorization (adsorption) ability of dead pellets during repeated batch studies. Astrazon Black dye was decolorized effectively, about 90%, by viable pellets of all fungi during the first use. Viable F. trogii pellets were found as the most effective pellets. Upon pellet treatment not only a high decolorization but also reduced toxicity (antimicrobial activity) of the Astrazon Black dye was recorded. This type of decolorization activity with commercial or crude laccase was partially observed. Growing cells of F. trogii in batch system showed lower efficiency in color removal of mixed dyes compared to the pre-grown pellets in repeated batch system. The results in this study showed that mycelial pellets could effectively be used as an alternative to traditional physicochemical processes.Öğe Facile construction of a robust and recyclable laccase/metal-organic framework-808 with boosted stability for biodegradation of Reactive Blue 171 and Reactive Blue 198 from aqueous media(Elsevier, 2024) Bakar, Busra; Bugday, Nesrin; Birhanli, Emre; Boran, Filiz; Ulu, Ahmet; Yasar, Sedat; Yesilada, OzferLaccase enzyme sees application demand in many industries such as textile, food processing, wood processing, pharmaceutical, and chemical. However, it becomes difficult to maintain the enzymatic activity of laccase under harsh reaction conditions and even after several biocatalytic cycles. Therefore, suitably prescribed supports are crucial to ensure that the catalytic activity and reusability of the immobilized laccase are maintained at high levels. The present study highlights the development and dye decolorization application of an enzyme carrier matrix employing a Zr-based metal-organic framework (MOF), MOF-808, with hierarchical porosity for the immobilization of laccase from Trametes trogii . The immobilization efficiency for Lac/MOF-808 was found to be 70.83 +/- 1.98 %. Lac/MOF-808 exhibited optimal catalytic temperature at 60 degrees C, while the optimal catalytic pH was 4.5. Due to recoverable properties from the carrier matrix the recycle test was satisfactory for the Lac/MOF808, being reused 7 times without losses greater than 50 % of residual activity. Stored at 25 degrees C, Lac/MOF-808 retained 30 % of its activity during 4-weeks period. A kinetic study was carried out for Lac/MOF-808 monitoring the oxidation reaction of ABTS. The K-m value was 0.070 mM and the V-max was 87.7 mu mol min(-1) g(-1). Kinetic investigations, on the other hand, demonstrated a decrease in K m following immobilization, signifying a higher affinity for substrate. The Lac/MOF-808 maintained its decolorization efficiency even after eight reaction cycles, exhibiting a remarkable activity of 56.7 % and 77.2 % against Reactive Blue 171 and Reactive Blue 198, respectively. Hence, the described Lac/MOF-808 might be an ideal candidate for efficient dye decolorization applications.Öğe Immobilization of Trametes trogii laccase on polyvinylpyrrolidone-coated magnetic nanoparticles for biocatalytic degradation of textile dyes(Taylor & Francis Ltd, 2024) Bakar, Busra; Birhanli, Emre; Ulu, Ahmet; Boran, Filiz; Yesilada, Ozfer; Ates, BurhanHigh cost and low operational stability are the most important challenges limiting the possible use of laccase in the removal of textile dyes. To overcome these challenges, in this study, polyvinylpyrrolidone (PVP)-coated magnetic nanoparticles (MNPs) were produced and characterized. To our knowledge, this is the first study to explore the feasibility of immobilizing a Trametes trogii laccase enzyme on Fe3O4/PVP MNPs. The characterization of samples and the successful immobilization of laccase were verified by characterization methods. Besides, the biochemical properties and stability of the Fe3O4/PVP/Lac were evaluated in terms of optimum pH, optimum temperature, thermostability, thermodynamic and kinetic parameters, storage stability, operational stability, and decolorization efficiency of two different textile dyes. The optimum activities were recorded at pH 2.5 degrees C and 30 degrees C. The Fe3O4/PVP/Lac displayed remarkable thermal stability and activation energy for denaturation, enthalpy, Gibbs free energy, and entropy results confirmed the enhanced stability of Fe3O4/PVP/Lac against high temperatures. Meanwhile, the Fe3O4/PVP/Lac retained about 58% of its original activity after seven consecutive reuses, while it retained up to 25% of its original activity after 28 d of storage at room temperature. K-m and V-max for the Fe3O4/PVP/Lac were calculated to be 126 mu M and 211 mu mol/min, respectively. Finally, after 8 and 6 cycles of repeated use, the Fe3O4/PVP/Lac still decolorized 32.34% and 32.23% of Remazol Brilliant Blue R (RBBR) and Indigo Carmine (IC), respectively. As envisioned, this study suggests a promising way to solve the problems of high price and poor operational stability of the enzyme during biocatalytic decolorization of textile dyes in wastewaters.Öğe Investigations of Hg(II) and Pb(II) tolerance, removal and bioaccumulation and their effects on antioxidant enzymes on thermophilic Exiguobacterium profundum(Taylor & Francis Inc, 2020) Akkoyun, Mahire Bayramoglu; Ozdemir, Sadin; Kilinc, Ersin; Birhanli, EmreHg(II) and Pb(II) tolerance, removal, bioaccumulation and effects on antioxidant enzymes of thermophilic Exiguobacterium profundum were investigated. The results indicated that Hg(II) was more toxic than Pb(II) to E. profundum. E. profundum was also more tolerant in solid medium than in liquid medium for Pb(II) and Hg(II). The bacterial growth was not significantly influenced at 1.0 and 2.5 mg/L Pb(II) and Hg(II) for 24 h. The highest Hg(II) and Pb(II) bioaccumulation amounts were determined as 37.56 and 54.35 mg metal/dried bacteria, respectively. Bioaccumulation capacities of the cell membrane of E. profundum for Hg(II) and Pb(II) were determined. The different concentrations of Pb(II) and Hg(II) enhanced the SOD and CAT enzymes. In addition, variations of the surface macrostructure and the functionality of E. profundum after the interaction with Hg(II) and Pb(II) were investigated by the scanning electron microscope (SEM) and the Fourier transform infrared spectroscopy (FT-IR), respectively. This investigation obviously showed that thermophilic E. profundum can also be applied for removal and recovery of toxic metals from industrial wastewater. Clearly, a further investigation should be utilized by thermophilic microorganisms. According to antioxidant enyzme activities, E. profundum can be also used as a bioindicator for the detection of toxic metal pollution in natural water samples.Öğe Laccase production by newly isolated white rot fungus Funalia trogii: Effect of immobilization matrix on laccase production(Elsevier Science Bv, 2013) Birhanli, Emre; Erdogan, Selim; Yesilada, Ozfer; Onal, YunusThe laccase production performance of newly isolated Funalia trogii (F. trogii) immobilized on low-cost activated adsorbents prepared from apricot stone was investigated in inexpensive molasses medium and compared with free pellets. The adsorbents were apricot stone-based activated carbon (AC), Cu-impregnated apricot stone-based activated carbon (Cu-AC) and Fe-impregnated apricot stone-based activated carbon (Fe-AC). Cu-AC and Fe-AC were prepared by chemical activation. The values of BET surface area (S-BET), total pore volume (V-t), micropore surface area (S-mic) and micropore volume (V-mic) which show the pore properties of the activated carbons were 133 m(2) g(-1), 0.105 cm(3) g(-1), 108 m(2) g(-1) and 0.056 cm(3) g(-1) for Cu-AC and 145 m(2) g(-1), 0.112 cm(3) g(-1), 117 m(2) g(-1) and 0.061 cm(3) g(-1) for Fe-AC, respectively. F. trogii attached well on all of these adsorbents. However, the fungus immobilized on Cu-AC produced much higher levels of laccase than the others. The laccase activity obtained in 5 g L-1 molasses media after first cycle and mean laccase activity obtained after three cycles with fungus immobilized on Cu-AC were 29.23 U mL(-1) and 27.04 U mL(-1), respectively. These activities were only 0.25 and 0.39 U mL(-1) with free pellets. The crude laccase from immobilized culture could also decolorize the textile dyes. (c) 2012 Elsevier B.V. All rights reserved.Öğe Laccase-conjugated thiolated chitosan-Fe3O4 hybrid composite for biocatalytic degradation of organic dyes(Elsevier, 2020) Ulu, Ahmet; Birhanli, Emre; Boran, Filiz; Koytepe, Suleyman; Yesilada, Ozfer; Ates, BurhanIn this study, a novel immobilization support for laccase was developed to enhance enzyme stability, efficiency and reusability. Firstly, Fe3O4 magnetic particles were synthesized and modified by the co-precipitation route using thiolated chitosan (TCS). The support was characterized using several methods. Afterward, laccase was attached to the surface of functional support. The biochemical properties of the immobilized laccase were comprehensively investigated. It was observed that immobilized laccase achieved maximum activity at pH 4.0 and the optimum temperature was found to be 50 degrees C. After storage at +4 degrees C and similar to 25 degrees C for 4 weeks, the residual activity of the immobilized laccase was 87% and 80% of its initial activity, respectively. At 55 degrees C, the activity of immobilized lactase decreased to 73A% in 180 min and after reused 20 times, the relative activity of immobilized laccase still was approximately 50% of its initial activity. Moreover, the textile dye (Reactive Blue 171 and Acid Blue 74) decolorization activity of immobilized laccase was also tested and it showed long-term textile dye decolorization activity. These results are promising for the use of laccase in industrial and biotechnological applications. Therefore, this functionalized magnetic hybrid composite might be used to immobilize laccase, an industrially important enzyme. (C) 2020 Elsevier B.V. All rights reserved.Öğe Mechanical and durability characteristics of GGBS-based self-healing geopolymer mortar produced using by an endospore-forming bacterium(Elsevier, 2022) Ekinci, Enes; Turkmen, Ibrahim; Birhanli, EmreHealing process of the gaps and cracks in the structure of geopolymer binders, which have emerged as greener alternatives compared to their traditional Portland cement counterparts, is of great importance in terms of a long economic life. The application of the microbial induced carbonate precipitation (MICP) method, which is the most striking of the various healing techniques applied to building materials, on geopolymer composites has been limited to a few successful studies. At this point, it is considered to be an important step to examine the effects of addition of bacteria on the mechanical and durability characteristics of geopolymer composites in detail. Therefore, this paper was designed to examine the effect of the usage of Bacillus subtilis on the mechanical and durability performance of ground blast furnace slag (GBFS)-based geopolymer mortar (GPM) specimens. In the GPM specimens activated with Na2SiO3, the total liquid/ binder ratio as 0.55 and the binder/fine aggregate ratio as 1:2 was kept constant. Bacterial cultures in liquid form prepared at different concentrations (109 and 107 CFU/mL) were added directly to the Na2SiO3 at 0, 1, 2 and 3% by weight of GBFS. GPM samples, which were prepared in seven different groups in total, were kept in three different curing mediums (precipitation medium, water and ambient conditions) from 7th day to the 28th day. After the curing period was over, the compressive strength, electrical resistivity, sulfate and acid resistance, capillary water absorption, splitting tensile strength and permeability properties were investigated on the GPM samples. In addition, the above-mentioned test results were confirmed by the microstructural analyzes performed. Experimental findings revealed that the optimum bacterial concentration and bacterial dosage values were 107 CFU/mL and 3%, respectively, in terms of both mechanical properties and durability performances. On the other hand, it was observed that all of the GPM specimens cured in precipitation medium (PM) and produced using bacteria had superior performances compared to their counterparts cured in water and ambient conditions. This situation clearly demonstrated that an effective self-healing process that will occur in GPM samples produced with the addition of bacteria directly could only be possible by creating a curing environment containing urea and calcium.Öğe Performance of self-healing geopolymer paste produced using Bacillus subtilis(Elsevier Sci Ltd, 2022) Ekinci, Enes; Turkmen, Ibrahim; Birhanli, EmreThis study examines the effects of the usage of bacteria as a self-healing agent on the geopolymer paste (GP) sample's characteristics. Examining the microbial self-healing capacity of geopolymer binders, which have many advantages over traditional Portland cement, is seen as an important and necessary step because of frequently studying innovative approaches on geopolymer samples. To carry out this investigation, GP samples produced using ground blast furnace slag (GBFS) were activated only with Na2SiO3. Bacillus subtilis was selected as the healing agent for the production of GP samples. As a result of the preliminary tests in which different variables (curing environment, sample content) were examined, it was decided what the sample content to be used in the main test processes. The bacterial suspensions were prepared at ratios of 107 and 109 CFU/mL. Bacterial samples prepared at two different cell densities were added to the mixture at 1, 2 and 3% by weight of the binder. The GP samples that cured under laboratory conditions until the end of the 7th day, were subjected to healing process in three different curing environments (water, air and precipitation medium consisting of urea, yeast extract and Ca (NO3)2.4H2O After the healing process was completed, the compressive strength, rheological behaviour, geopolymerization kinetics, physical properties, microstructural and visual examinations were performed. Experimental findings demonstrated that the self-healing mechanism resulting from the metabolic activity of Bacillus subtilis can be successfully applied in geopolymer composites in terms of high durability and mechanical properties.Öğe Poly(2-hydroxyethyl methacrylate)/boric acid composite hydrogel as soft contact lens material: Thermal, optical, rheological, and enhanced antibacterial properties(Wiley, 2018) Ulu, Ahmet; Balcioglu, Sevgi; Birhanli, Emre; Sarimeseli, Ayse; Keskin, Rukiye; Koytepe, Suleyman; Ates, BurhanThe present work proposes to fabricate a composite hydrogel material that well characterized, transparent, biocompatible, and self-antibacterial as potential soft contact lens material. For this purpose, poly(2-hydroxyethyl methacrylate) (PHEMA)/boric acid (BA) composite hydrogels were successfully prepared by chemical crosslinking with BA through in situ polymerization using different BA ratios between 1 and 10% w/w. Afterward, the compositions, thermal stability, transparence, oxygen permeability, water uptake capacity, swelling ratio as well as morphological and rheological properties, in vitro degradability, in vitro cytotoxicity, and antibacterial properties of the all prepared materials were analyzed using a series of different techniques. The thermal stability, hydrophilicity, water uptake, oxygen permeability gradually increased depending ratio of BA, which is desirable for biomaterial. While the transparence and refractive index decreased, the composite hydrogels, except for BA content of 10 wt %, maintained enough transparency to be used for contact lens. In addition, PHEMA/BA composite hydrogels exhibited good cytocompatibility (PHEMA-1%BA and PHEMA-3%BA) and excellent antibacterial activity against Gram-positive (Staphylococcus aureus and Enterococcus faecium) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Overall, the results demonstrated that the obtained PHEMA/BA composite hydrogels could be considered as self-antibacterial contact lens and a potential composite biomaterial for other applications. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46575.Öğe Preparation, characterization, and evaluation of multi-biofunctional properties of a novel chitosan-carboxymethylcellulose-Pluronic P123 hydrogel membranes loaded with tetracycline hydrochloride(Elsevier, 2022) Ulu, Ahmet; Aygun, Tugba; Birhanli, Emre; Ates, BurhanHerein, we report a multifunctional hydrogel membrane with good mechanical properties, excellent antioxidant efficiency, and broad-spectrum antimicrobial activity. For this purpose, a series of chitosan-carboxymethyl cellulose-Pluronic P123 (CHT-CMC-P123) hydrogel membranes were prepared by blending various tetracycline hydrochloride (TCH) contents. The physicochemical and biological properties of CHT-CMC-P123 membranes were comprehensively investigated. With the increase of TCH content from 5 % to 20 %, hydrogel membranes presented a decreased water contact angle from 18.96 degrees to 11.24 degrees, and a decreased water vapor transmission rate from 171.8 to 156.1 g/m2 h. Besides, with the increase of TCH content (5-20 %), the tensile strength (0.31-0.11 MPa) and elongation at break (10.57-4.82 %) of hydrogel membranes decreased while their thickness increased (113.5-324.3 mu m). The data show that the release of TCH reached equilibrium after 26 days, with a cumulative percentage of approximately 28 %-87 %. Moreover, the hydrogel membranes exhibited a high antioxidant ca-pacity of-92 % for DPPH radical. Importantly, the incorporation of TCH significantly (-2.3 fold) enhanced the antimicrobial activity of the hydrogel membranes against Gram-positive, and Gram-negative bacteria and yeast. Based on our findings, these hydrogel membranes with superior properties may serve as effective food packaging and wound healing materials.Öğe Resistance, removal, and bioaccumulation of Ni (II) and Co (II) and their impacts on antioxidant enzymes of Anoxybacillus mongoliensis(Elsevier Science Inc, 2020) Akkoyun, Mahire Bayramoglu; Ozdemir, Sadin; Kilinc, Ersin; Birhanli, Emre; Aygun, Aysenur; Sen, FatihIn this study, it was hypothesis that A. mongoliensis could be used as bioindicator for Ni (II) and Co (II). Thus, Ni (II) and Co (II) resistance, removal, bioaccumulation, and the impacts of them on antioxidant enzyme systems of thermophilic Anoxybacillus mongoliensis were investigated in details. The bioaccumulation of Ni (II) and Co (II) on the cell membrane of thermophilic A. mongoliensis, variations on surface macrostructure and functionality by FT-IR and SEM, and determination of antioxidant enzyme activities were also tested. The highest bioaccumulation values of Co (II) and Ni (II) were detected as 102.0 mg metal/g of dry bacteria at 10 mg/L for the 12th h and 90.4 mg metal/g of dry bacteria for the 24th h, respectively, and the highest Ni (II) and Co (II) cell membrane bioaccumulation capacities of A. mongoliensis were determined as 268.5 and 274.9 mg metal/g wet membrane, respectively at the 24th h. In addition, increasing on SOD and CAT activities were observed on depend of concentration of Ni (II) and Co (II) with respect to control. The antioxidant enzyme activity results also indicated that A. mongoliensis might be used as a bioindicator for Ni (II) and Co (II) pollution in environmental water specimens.Öğe Synthesis and characterization of whitlockite from sea urchin skeleton and investigation of antibacterial activity(Elsevier Sci Ltd, 2021) Yucel, Aysegul; Sezer, Selda; Birhanli, Emre; Ekinci, Tuba; Yalman, Emine; Depci, TolgaIn the present study, undoped whitlockite and ZnO doped-Whitlockite, which is the second most abundant inorganic material in bone structure, were synthesized from sea urchin skeleton. The obtained bioceramic ma-terials were characterized by XRD, FT-IR, and SEM and their antibacterial activities were determined using the inhibition zone diameters of Escherichia coli and Pseudomonas aeruginosa as gram negative bacteria and Staphylococcus aureus as gram positive bacterium after 24 h incubation. The characterization studies showed that nano size homogenous biocereamic whitlockite (Ca2.86Mg0.14(PO4)(2)) was synthesized from the sea urchin skeleton. After dopping process, the main structure of the whitlockite keeps stable, showing a dopping concentration-independent character. On the other hand, the peaks belonging to ZnO were started to seen in the XRD pattern with increasing the level of ZnO-concentration (after 7 %). All experimental results point out that the obtained whitlockites are viable nominate candidates for bioceramic materials and the results of antibacterial sensitivity prove the inhibitory effect towards Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus for ZnO-doped-whitlockite.Öğe Tailor-made novel electrospun polycaprolactone/polyethyleneimine fiber membranes for laccase immobilization: An all-in-one material to biodegrade textile dyes and phenolic compounds(Pergamon-Elsevier Science Ltd, 2023) Kolak, Seda; Birhanli, Emre; Boran, Filiz; Bakar, Buesra; Ulu, Ahmet; Yesilada, Ozfer; Ates, BurhanIn spite of many works on the biodegradation of textile dyes and phenolic compounds, we propose a new, inexpensive, environmentally friendly, and sustainable material based on electrospun fiber and immobilized laccase. The polycaprolactone (PCL)/polyethyleneimine (PEI) electrospun fibers were optimized and prepared by electrospinning technique according to the operational parameters like PCL concentration (12 wt%), PEI con-centration (10 wt%), voltage (16 kV), needle tip-collector distance (20 cm), and injection speed (0.7 mL/h). Next, characterization studies were performed to investigate the morphology and structure of the electrospun fibers without and with laccase. The crude laccase was obtained by cultivating the white rot fungus T. trogii (TT), and T. versicolor (TV). The resulting electrospun fibers showed a smooth surface with a mean diameter of around 560 nm, and larger diameters were observed after laccase immobilization. According to the results, immobili-zation increased the stability properties of laccase such as storage, and operational. For instance, the residual activity of the PCL/PEI/TTL and PCL/PEI/TVL after 10 repeated cycles, was 33.2 & PLUSMN; 0.2% and 26.0 +/- 0.9%, respectively. After 3 weeks of storage, they retained around 30% of their original activity. Moreover, the PCL/ PEI/TTL and PCL/PEI/TVL were found to possess high decolorization yield to remove Orange II and Malachite Green textile dyes from solutions imitating polluted waters. Among them, the PCL/PEI/TTL exhibited the highest decolorization efficiencies of Orange II and Malachite Green after 8 continuous uses at pH 5 and a temperature of 50 C, reaching over 86%, and 46%, respectively. Moreover, PCL/PEI/TTL and PCL/PEI/TVL effectively degraded the 2,6-dichlorophenol phenolic compound at an optimal pH and temperature range and exhibited maximum removal efficiency of 52.6 +/- 0.1% and 64.5 +/- 7.6%, respectively. Our approach combines the ad-vantageous properties of electrospun fiber material and immobilization strategy for the efficient use of industrial scale important enzymes such as laccase in various enzymatic applications.Öğe Tunable and tough porous chitosan/?-cyclodextrin/tannic acid biocomposite membrane with mechanic, antioxidant, and antimicrobial properties(Elsevier, 2021) Ulu, Ahmet; Birhanli, Emre; Ates, BurhanHerein, tannic acid (TA)-reinforced chitosan (CHS)/beta-cyclodextrin (beta-CD) biocomposite membranes were prepared by TA solution incubating treatment. The functional groups, crystal structure, and morphological characterizations of the prepared biocomposite membranes were investigated using various methods. The biocomposite membranes were investigated in terms of their wettability, porosity, swelling degree, and water uptake. In vitro antioxidant investigation was carried out through DPPH assay. Moreover, the prepared biocomposite membranes were evaluated for their antimicrobial ability against three different microbial species. The introduction of TA effectively improved the swelling behavior, mechanical strength, and porosity of the biocomposite membranes. TA increased the tensile strength from 0.7 +/- 0.2 MPa to a maximum of 2.2 +/- 0.6 MPa and elongation at break from 26.9 +/- 0.7% to a maximum of 36.7 +/- 3.5%. The biocomposite membranes showed an initial burst release of TA (similar to 40%) within 6 h, followed by a gradual release of 100% by 18 h. Furthermore, the introduction of TA into the biocomposite membranes further improved the antimicrobial activities against both bacteria and yeast, as well as the in vitro antioxidant potential. As a consequence, the prepared biocomposite membranes could potentially be used as scaffold in broaden biomedical fields due to their adaptable structure, porosity, greatly antioxidant, and antimicrobial activity.
