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Article Citation - WoS: 2Citation - Scopus: 2Biosorption of Reactive Dyes by Novel Bacterium Leclercia Adecarboxylata: Complete Removal of Reactive Black 5 and Molecular Insights Into the Adsorption Mechanism(Wiley, 2025) Sen, Seda; Korkmaz, Filiz; Kilic, Nur KocberberLeclercia adecarboxylata isolated from the D & uuml;den Waterfall (Turkey) was utilized as a biosorbent for the removal of Reactive Black 5 (RB5), Setazol Blue BRF-X (BRF-X), Setazol Navy Blue SBG (SNB), and Setazol Turquoise Blue G (STBG). Of the dyes, RB5 was removed with the highest efficiency, 97.4% after 60 min. The effect of parameters such as pH (3-9), initial biosorbent dose (0.1-2.0 g/L), and initial dye concentration (25-1200 mg/L) on the biosorption of RB5 was investigated. Increasing the biosorbent dosage from 0.1 to 2.0 g/L enhanced the RB5 removal from 55.3% to 100% within 10 min. The complete removal (100%) of RB5 was achieved in media with 2.0 g/L biosorbent and 25 mg/L RB5 at pH 3 after 10 min. Additionally, the soluble extracellular polymeric substances (EPS) of L. adecarboxylata were found to consist of proteins, lipids, nucleic acids, and polysaccharides according to Fourier transform infrared spectroscopy (FTIR) analysis. The EPS was found to play a crucial role in dye removal, forming chemical interactions with dye molecules. Zeta potential analysis was used to evaluate the charge distribution on the biosorbent surface (-12.6 +/- 1.1 mV) and its interactions in the biosorption process. Kinetic and isotherm models suggested a complex interaction mechanism between the biomass and the dye. Adsorption isotherm data were analyzed via nine isotherm models. Among them, the Hill model was found to be the best fit for describing the equilibrium adsorption process of the RB5 (R2 = 0.9993). Overall, the applied models elucidated the influence of both physical and chemical interactions on the mechanism. Kinetic studies revealed that the adsorption of RB5 fit a pseudo-second-order kinetic model. The unique biochemical composition of the indigenous L. adecarboxylata biosorbent provided a high affinity for RB5, offering a sustainable, rapid, and economical solution for the treatment of dye-polluted water.Article Citation - WoS: 9Citation - Scopus: 9Ir-Spectroscopic Characterization of an Elongated Ompg Mutant(Elsevier Science inc, 2015) Korkmaz, Filiz; van Pee, Katharina; Yildiz, OezkanOmpG is a nonselective, pH dependent outer membrane protein from Escherichia coli. It consists of 281 residues, forming a 14-stranded beta-sheet structure. In this study, OmpG is extended by 38 amino acids to produce a 16-stranded beta-barrel (OmpG-16S). The resulting protein is investigated by IR-spectroscopy. The secondary structure, pH-dependent opening/closing mechanism, buffer accessibility and thermal stability of OmpG-16S are compared to OmpG-WT. The results show that OmpG-16S is responsive to pH change as indicated by the Amide I band shift upon a switch from acidic to neutral pH. This spectral shift is consistent with that observed in OmpG-WT, which confirms the existence of structural differences consistent with the presence of the open or closed state. Secondary structure analysis after curve-fitting of Amide I band revealed that the additional residues do not fold into beta-sheet; rather they are in the form of turns and unordered structure. In thermal stability experiments, OmpG-16S is found to be as stable as OmpG-WT. Additionally, H/D exchange experiments showed no difference in the exchange rate of OmpG-16S between the acidic and alkaline pH, suggesting that the loop L6 is no longer sufficient to block the pore entrance at acidic pH. (C) 2015 Elsevier Inc. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 4Nanoremediation of Toxic Dyes Using a Bacterial Consortium Immobilized on Cellulose Acetate Nanofiber Mats(Wiley, 2024) Erkoc, Esra; Tuzun, Imre; Korkmaz, Filiz; San Keskin, Nalan Oya; Kocberber Kilic, NurStenotrophomonas maltophilia and Ochrobactrum sp. demonstrated the highest rates of dye bioremediation. The trials were performed at pH 8, which resulted in the highest bioremediation rate of 64.6% in media containing 21.2 mg L-1 dye. As the dye concentration increased, the pollutant removal decreased, with the maximum bioremoval rate of 70.3%. The removal capacity was increased with an increase in biomass concentration; the highest yield of 91.3% was obtained in media containing 14.2 mg L-1 dye and 12% (v/v) biomass. In nanoremediation studies, the bacterial consortium was immobilized on cellulose acetate nanofiber mats (CA-NFM). Scanning electron microscopic micrographs showed that bead-free nanofiber mats were effective in immobilizing bacterial cells. Moreover, nanofiber structures were capable of supporting exopolysaccharides formation, as confirmed by Fourier transform & imath;nfrared spectroscopy. The bacterial consortium immobilized on CA-NFM showed a maximum bioremoval rate of 56.5%. Reusability tests demonstrated that the consortium immobilized CA-NFM could be used at least five times. Furthermore, after leaving the mat for 1 month at 4 degrees C, it was still usable, and the removal efficiency was found to be 45.4%. Based on our findings, bacteria immobilized on CA-NFM have the potential to be used as highly effective and versatile nanobiotechnological biological sorbents in the treatment of wastewater containing dyes.Article Structural and Electronic Properties of the Dppc Molecule(World Scientific Publ Co Pte Ltd, 2006) Erkoc, Sakir; Korkmaz, FilizThe structural and electronic properties of the DPPC molecule have been investigated theoretically by performing semi-empirical self-consistent-field molecular-orbital theory calculations at the PM3 level in its ground state.Article Simultaneous Removal of Setazol Navy Blue and Cr(vi) by Mixed Microbial Culture Isolated From the Çubuk Stream(Springer int Publ Ag, 2024) Gunduz, A. Irem; Erkoc, Esra; Korkmaz, Filiz; Kilic, Nur KocberberWater samples taken from the & Ccedil;ubuk Stream (Ankara, Turkey) were inoculated into nutrient broth media containing Setazol Navy Blue SBG (SNB), an organic pollutant, and heavy metal Cr(VI), an inorganic pollutant, to obtain a pollutant-resistant mixed microbial culture. Experiments were conducted with this culture to remove SNB and heavy metal. The optimum conditions, where the mixed bacterial culture removed the pollutants most effectively, were determined, showing that the highest capacity for removal took place at pH 8 with removal percentages 96.3% for Cr(VI) and 78.5% for SNB. In media with 50.4 mg/L SNB and 9.7 mg/L Cr(VI), the SNB removal was 87.3%, and the Cr(VI) removal was 96.6% at the end of the 7-day incubation period. The highest removal was observed with a biomass concentration of 8% (v/v) of mixed culture [50 mg/L SNB dye+25 mg/L Cr(VI)]. The removal was 100% for both Cr(VI) and the SNB dye. The bacteria with the highest removal were isolated and identified using 16S rDNA gene sequence analysis as Microbacterium oxydans and Leucobacter aridicollis. The role of various functional groups and the structures of the microorganisms that might be involved in the removal mechanisms were discussed using their FTIR spectra. This report is the first study that investigates a mixed bacterial culture and pure cultures (M. oxydans and L. aridicollis) isolated from that mixed culture, removing both SNB and Cr(VI) simultaneously.
