Omer Faruk Sarioglu

Efficient ammonium removal from aquatic environments by Acinetobacter calcoaceticus STB1 immobilized on an electrospun cellulose acetate nanofibrous web.

A novel biocomposite material was developed by immobilizing an ammonia-oxidizing bacterial strain, Acinetobacter calcoaceticus STB1, on an electrospun porous cellulose acetate (CA) nanofibrous web. Ammonium removal characteristics of the STB1 immobilized CA nanofibrous web were determined at varying initial ammonium concentrations, and removal rates of 100%, 98.5% and 72% were observed within 48 h for 50 mg L−1, 100 mg L−1 and 200 mg L−1 samples, respectively. Most of the ammonia is inferred to be converted into nitrogen or is accumulated as bacterial biomass, as only trace amounts of ammonium were converted into nitrite or nitrate. Reusability test results indicate that, at an initial ammonium concentration of 100 mg L−1, bacteria-immobilized CA nanofibrous webs can be reused for at least 5 cycles. SEM images of the STB1/CA nanofibrous web after five cycles of reuse and rigorous washing demonstrate that bacterial biofilms strongly adhere to nanofiber surfaces.

Removal of a reactive dye and hexavalent chromium by a reusable bacteria attached electrospun nanofibrous web

A contaminant resistant Lysinibacillus sp. NOSK was isolated from a soil sample and its Reactive Black 5 (RB5) and Cr(VI) removal efficiencies were investigated as a function of changes in the initial pH values, temperature, static/shaking conditions, reactive dye and Cr(VI) concentrations. In this study, an electrospun polysulfone nanofibrous web (PSU-NFW) was found to be effective in attachment of bacterial cells. Bacteria attached PSU-NFWs (bacteria/PSU-NFW) have shown highly efficient removal of RB5, as 99.7 ± 0.9% and 35.8 ± 0.4% for the pristine PSU-NFW. Moreover, the highest Cr(VI) removal efficiencies measured were 98.2 ± 0.6% for bacteria attached PSU-NFW and 32.6 ± 0.6% for the pristine PSU-NFW. Simultaneous removal of RB5 and Cr(VI) were also investigated. Reusability test results indicate that, bacteria/PSU-NFW can be reused for at least 7 cycles with 28.1 ± 0.6% and 66.7 ± 0.8% removal efficiencies for RB5 and Cr(VI), respectively.

Evaluation of contact time and fiber morphology on bacterial immobilization for development of novel surfactant degrading nanofibrous webs

Novel electrospun fibrous biocomposites were developed by immobilizing two different sodium dodecyl sulfate (SDS) biodegrading bacterial strains, Serratia proteamaculans STB3 and Achromobacter xylosoxidans STB4 on electrospun non-porous cellulose acetate (nCA) and porous cellulose acetate (pCA) webs. The required contact time for bacterial immobilization was determined by SEM imaging and viable cell counting of the immobilized bacteria, and bacterial attachment was ended at day 25 based on these results. SDS biodegradation capabilities of bacteria immobilized webs were evaluated at different concentrations of SDS, and found to be highly efficient at concentrations up to 100 mg L−1. It was observed that SDS remediation capabilities of bacteria immobilized webs were primarily based on the bacterial existence and very similar to the free-bacterial cells. A reusability test was applied on the two most efficient webs (STB3/pCA and STB4/pCA) at 100 mg L−1 SDS, and the results suggest that the webs are potentially reusable and improvable for SDS remediation in water. SEM images of bacteria immobilized webs after the reusability test demonstrate strong bacterial adhesion onto the fibrous surfaces, which was also supported by the viable cell counting results. Our results are highly promising and suggest that bacteria immobilized electrospun fibrous webs have the potential to be used effectively and continually for remediation of SDS from aqueous environments.

Bacteria encapsulated electrospun nanofibrous webs for remediation of methylene blue dye in water

In this study, preparation and application of novel biocomposite materials that were produced by encapsulation of bacterial cells within electrospun nanofibrous webs are described. A commercial strain of Pseudomonas aeruginosa which has methylene blue (MB) dye remediation capability was selected for encapsulation, and polyvinyl alcohol (PVA) and polyethylene oxide (PEO) were selected as the polymer matrices for the electrospinning of bacteria encapsulated nanofibrous webs. Encapsulation of bacterial cells was monitored by scanning electron microscopy (SEM) and fluorescence microscopy, and the viability of encapsulated bacteria was checked by live/dead staining and viable cell counting assay. Both bacteria/PVA and bacteria/PEO webs have shown a great potential for remediation of MB, yet bacteria/PEO web has shown higher removal performances than bacteria/PVA web, which was probably due to the differences in the initial viable bacterial cells for those two samples. The bacteria encapsulated electrospun nanofibrous webs were stored at 4°C for three months and they were found as potentially storable for keeping encapsulated bacterial cells alive. Overall, the results suggest that electrospun nanofibrous webs are suitable platforms for preservation of living bacterial cells and they can be used directly as a starting inoculum for bioremediation of water systems.

Bacteria-immobilized electrospun fibrous polymeric webs for hexavalent chromium remediation in water

The development of hexavalent chromium remediating fibrous biocomposite mats through the immobilization of a hexavalent chromium reducing bacterial strain, Morganella morganii STB5, on the surfaces of electrospun polystyrene and polysulfone webs is described. The bacteria-immobilized biocomposite webs have shown removal yields of 93.60 and 93.79xa0% for 10xa0mg/L, 99.47 and 90.78xa0% for 15xa0mg/L and 70.41 and 68.27xa0% for 25xa0mg/L of initial hexavalent chromium within 72xa0h, respectively, and could be reused for at least five cycles. Storage test results indicate that the biocomposite mats can be stored without losing their bioremoval capacities. Scanning electron microscopy images of the biocomposite webs demonstrate that biofilms of M. morganii STB5 adhere strongly to the fibrous polymeric surfaces and are retained after repeated cycles of use. Overall, the results suggest that reusable bacteria-immobilized fibrous biocomposite webs might be applicable for continuous hexavalent chromium remediation in water systems.Graphical Abstract

Comparative serum albumin interactions and antitumor effects of Au(III) and Ga(III) ions.

In the present study, interactions of Au(III) and Ga(III) ions on human serum albumin (HSA) were studied comparatively via spectroscopic and thermal analysis methods: UV-vis absorbance spectroscopy, fluorescence spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and isothermal titration calorimetry (ITC). The potential antitumor effects of these ions were studied on MCF-7 cells via Alamar blue assay. It was found that both Au(III) and Ga(III) ions can interact with HSA, however; Au(III) ions interact with HSA more favorably and with a higher affinity. FT-IR second derivative analysis results demonstrated that, high concentrations of both metal ions led to a considerable decrease in the α-helix content of HSA; while Au(III) led to around 5% of decrease in the α-helix content at 200μM, it was around 1% for Ga(III) at the same concentration. Calorimetric analysis gave the binding kinetics of metal-HSA interactions; while the binding affinity (Ka) of Au(III)-HSA binding was around 3.87×10(5)M(-1), it was around 9.68×10(3)M(-1) for Ga(III)-HSA binding. Spectroscopy studies overall suggest that both metal ions have significant effects on the chemical structure of HSA, including the secondary structure alterations. Antitumor activity studies on MCF7 tumor cell line with both metal ions revealed that, Au(III) ions have a higher antiproliferative activity compared to Ga(III) ions.

Encapsulation of Living Bacteria in Electrospun Cyclodextrin Ultrathin Fibers for Bioremediation of Heavy Metals and Reactive Dye from Wastewater

Cyclodextrins (CD) are cyclic oligosaccharides produced from the enzymatic degradation of starch as a white powder form; on the other hand, they can be transformed into ultrathin electrospun fiber form by electrospinning technique. The electrospun cyclodextrin fibers (CD-F) can be quite attractive materials to encapsulate bacteria for bioremediation purposes. For instance, CD-F not only serve as a carrier matrix but also it serves as a feeding source for the encapsulated bacteria. In the present study, we demonstrate a facile approach by encapsulation of bacteria into CD-F matrix for wastewater treatment application. The natural and non-toxic properties of CD-F render a better bacterial viability for fibrous biocomposite. The encapsulated bacteria in CD-F exhibit cell viability for more than 7days at 4°C storage condition. Furthermore, we have tested the bioremediation capability of bacteria/CD-F biocomposite for the treatment of heavy metals (Nickel(II) and Chromium(VI)) and textile dye (Reactive Black 5, RB5). The bacteria/CD-F biocomposite has shown removal efficiency of Ni(II), Cr(VI) and RB5 as 70±0.2%, 58±1.4% and 82±0.8, respectively. As anticipated, the pollutants removal capabilities of the bacteria/CD-F was higher compare to free bacteria since bacteria can use CD as an extra carbon source which promotes their growth rate. This study demonstrates that CD-F are suitable platforms for the encapsulation of bacterial cells to develop novel biocomposites that have bioremediation capabilities for wastewater treatment.

Comparison of Au(III) and Ga(III) Ions’ Binding to Calf Thymus DNA: Spectroscopic Characterization and Thermal Analysis

Metals have been studied as potential chemotherapeutic agents for cancer therapies due to their high reactivity toward a wide variety of substances. The characterization of metal ion-binding capacities is essential to understand the possible effects of metals on target biomolecules. In the present study, biochemical effects of Au(III) and Ga(III) ions on calf thymus DNA (ctDNA) were studied comparatively via bioanalytical, spectroscopic, and thermal methods. Briefly, UV-Vis absorbance spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy were utilized for spectroscopic characterization, and isothermal titration calorimetry (ITC) measurements were performed for thermal analysis. Our results reveal that both Au(III) and Ga(III) ions are capable of interacting with ctDNA, and Au(III) ions display a more favorable interaction and a higher binding affinity. ITC analyses indicate that the Au(III)-DNA interaction displays a binding affinity (Ka) around 1.43u2009×u2009106xa0M−1, while a Ka around 1.17u2009×u2009105xa0M−1 was observed for the Ga(III)-DNA binding. It was suggested that both metal ions are unlikely to change the structural B-conformation while interacting with ctDNA.

Fourier Transform Infrared Spectroscopy as a Novel Approach for Analyzing the Biochemical Effects of Anionic Surfactants on a Surfactant-Degrading Arcobacter Butzleri Strain

Anionic surfactant-biodegrading capability of an Arcobacter butzleri strain was analyzed under aerobic conditions. The A. butzleri isolate displayed efficient surfactant-biodegrading capacity for sodium dodecyl sulfate (SDS) at concentrations of up to 100 mg/L in 6 days, corresponding to 99.0% removal efficiency. Fourier transform infrared spectroscopy was applied to observe the effects of varying concentrations of SDS on the biochemistry of bacterial cells. Results suggest that protein secondary structures were altered in bacterial cells at sufficiently high SDS concentrations, concurrent with SDS biodegradation.

Bacteria immobilized electrospun polycaprolactone and polylactic acid fibrous webs for remediation of textile dyes in water

In this study, preparation and application of novel biocomposite materials for textile dye removal which are produced by immobilization of specific bacteria onto electrospun nanofibrous webs are presented. A textile dye remediating bacterial isolate, Clavibacter michiganensis, was selected for bacterial immobilization, a commercial reactive textile dye, Setazol Blue BRF-X, was selected as the target contaminant, and electrospun polycaprolactone (PCL) and polylactic acid (PLA) nanofibrous polymeric webs were selected for bacterial integration. Bacterial adhesion onto nanofibrous webs was monitored by scanning electron microscopy (SEM) imaging and optical density (OD) measurements were performed for the detached bacteria. After achieving sufficient amounts of immobilized bacteria on electrospun nanofibrous webs, equivalent web samples were utilized for testing the dye removal capabilities. Both bacteria/PCL and bacteria/PLA webs have shown efficient remediation of Setazol Blue BRF-X dye within 48xa0hxa0at each tested concentration (50, 100 and 200xa0mg/L), and their removal performances were very similar to the free-bacteria cells. The bacteria immobilized webs were then tested for five times of reuse at an initial dye concentration of 100xa0mg/L, and found as potentially reusable with higher bacterial immobilization and faster dye removal capacities at the end of the test. Overall, these findings suggest that electrospun nanofibrous webs are available platforms for bacterial integration and the bacteria immobilized webs can be used as starting inocula for use in remediation of textile dyes in wastewater systems.