Nazime Mercan Dogan

Chromium(VI) bioremoval by pseudomonas bacteria: role of microbial exudates for natural attenuation and biotreatment of Cr(VI) contamination

Laboratory batch and column experiments were conducted to investigate the role of microbial exudates, e.g., exopolymeric substance (EPS) and alginic acid, on microbial Cr(VI) reduction by two different Pseudomonas strains (P. putida P18 and P. aeuroginosa P16) as a method for treating subsurface environment contaminated with Cr(VI). Our results indicate that microbial exudates significantly enhanced microbial Cr(VI) reduction rates by forming less toxic and highly soluble organo-Cr(III) complexes despite the fact Cr(III) has a very low solubility under the experimental conditions studied (e.g., pH 7). The formation of soluble organo-Cr(III) complexes led to the protection of the cells and chromate reductases from inactivation. In systems with no organic ligands, soluble organo-Cr(III) end products were formed between Cr(III) and the EPS directly released by bacteria due to cell lysis. Our results also provide evidence that cell lysis played an important role in microbial Cr(VI) reduction by Pseudomonas bacteria due to the release of constitutive reductases that intracellularly and/or extracellularly catalyzed the reduction of Cr(VI) to Cr(III). The overall results highlight the need for incorporation of the release and formation of organo-Cr(III) complexes into reactive transport models to more accurately design and monitor in situ microbial remediation techniques for the treatment of subsurface systems contaminated with Cr(VI).

Role of microbial exopolymeric substances (EPS) on chromium sorption and transport in heterogeneous subsurface soils: I. Cr(III) complexation with EPS in aqueous solution

Chromium (III) binding by exopolymeric substances (EPS) isolated from Pseudomonas putida P18, Pseudomonas aeruginosa P16 and Pseudomonas stutzeri P40 strains were investigated by the determination of conditional stability constants and the concentration of functional groups using the ion-exchange experiments and potentiometric titrations. Spectroscopic (EXAFS) analysis was also used to obtain information on the nature of Cr(III) binding with EPS functional groups. The data from ion-exchange experiments and potentiometric titrations were evaluated using a non-electrostatic discrete ligand approach. The modeling results show that the acid/base properties of EPSs can be best characterized by invoking four different types of acid functional groups with arbitrarily assigned pK(a) values of 4, 6, 8 and 10. The analysis of ion-exchange data using the discrete ligand approach suggests that while the Cr binding by EPS from P. aeruginosa can be successfully described based on a reaction stoichiometry of 1:2 between Cr(III) and HL(2) monoprotic ligands, the accurate description of Cr binding by EPSs extracted from P. putida and P. stutzeri requires postulation of 1:1 Cr(III)-ligand complexes with HL(2) and HL(3) monoprotic ligands, respectively. These results indicate that the carboxyl and/or phosphoric acid sites contribute to Cr(III) binding by microbial EPS, as also confirmed by EXAFS analysis performed in the current study. Overall, this study highlights the need for incorporation of Cr-EPS interactions into transport and speciation models to more accurately assess microbial Cr(VI) reduction and chromium transport in subsurface systems, including microbial reactive treatment barriers.

Role of microbial exopolymeric substances (EPS) on chromium sorption and transport in heterogeneous subsurface soils: II. Binding of Cr(III) in EPS/soil system

Laboratory batch sorption and column experiments were performed to investigate the effects of microbial EPSs isolated from Pseudomonas putida P18, Pseudomonas aeruginosa P16 and Pseudomonas stutzeri P40 on Cr(III) mobility in heterogeneous subsurface soils. Our batch and column results indicate that microbial EPS may have a pronounced effect on Cr(III) sorption and transport behavior depending on system conditions (e.g., pH, type of EPS). While EPS had no effect on Cr(III) sorption at pH<5, it led to a significant decrease in Cr(III) sorption under slightly acidic to alkaline pH range. Column experiments performed at pH 7.9 suggest that, in the presence of EPS, chromium(III) was significantly mobilized relative to non-EPS containing system due to the formation less sorbing and highly soluble Cr-EPS complexes and competition of EPS against Cr for surface sites. A two-site non-electrostatic surface chemical model incorporating a discrete ligand approach for the description of Cr-EPS interactions accurately predicted Cr(III) sorption and transport behavior in the presence of EPS under variable chemical conditions. Our simulations show that an accurate description of Cr(III) transport in the presence of EPS requires incorporation of proton and Cr(III) binding by EPS, EPS binding by soil minerals, Cr(III) binding by soil minerals, and ternary Cr(III)-EPS surface complexes into the transport equations. Although this approach may not accurately describe the actual mechanisms at the molecular level, it can improve our ability to accurately describe the effects of EPS on Cr(III) mobility in subsurface environment relative to the use of distribution coefficients (K(d)).

Reduction of Cr(VI) to Cr(III) by thermal Bacillus licheniformis B22 under different temperatures using binary and ternary combinations of organic acids

AbstractThis study presents optimization of process variables for hexavalent chromium reduction using thermotolerant Bacillus licheniformis B22 isolated from Pamukkale (Denizli, Turkey). We examined the effects of binary and ternary combinations of different electron-donating substrates (galacturonic acid, glucuronic acid, and humic acid) at 45 and 50°C. The influence of different pH values (6.0, 7.0, 8.0, 9.0, and 10.0) and initial inoculation rates (2, 4, 6, and 8%) were also enumerated. The strongest stimulatory effect on Cr(VI) reduction was obtained with ternary combination of galacturonic acid, glucuronic acid, and humic acid. At 45 and 50°C, 8% inoculation rate, the reduction in ternary combination is relatively fast, completely reducing 100 mg/l Cr(VI) in 6 h compared with 2% inoculation rate (12 h). This bacterium exhibited a rapid Cr(VI) reduction ability under optimized conditions. Cr(VI) reduction of B. licheniformis B22 increased with an increase in initial inoculation rate, and the optimum i...

Antibiotic Susceptibilities and SDS-PAGE Protein Profiles of Methicillin-Resistant Staphylococcus Aureus (MRSA) Strains Obtained from Denizli Hospital

In both HA-MRSAs and CAMRSAs are refered to as a significant factor of serious infections in high morbidity and mortality including bacteremia, pneumonia, endocarditis, osteomyelitis and toxic shock syndrome [2,3,4,5,6]. The factors that increase the prevalence of nosocomial bacteremia are the increase in older age groups in society, life period prolongation of people with chronic diseases, widespread use of immunosuppressive drugs, increase in interventional procedures for the purposes of diagnostic and therapeutic. Generally, some of staphylococ infections are nasocomial, other infections have occured by depending on MRSAs. The colonization rate with MRSA has increased in parallel duration of hospitalization. These strains have been found resistant against penicillins, combinations of betalactam/betalactamase inhibitory, sephalosporins, combinations of monobactames and carpenemes. To identify the resistance of staphylococcus’s against methycillin antibiotic, those methods as of disc diffusion, tube dilution or microdilution, agar scanning, agar dilution, automatise susceptibility tests, DNA hybridisation technics and polimeraze chain reaction have been used [7,8,9]. The aim of this study is to identify antibiotic susceptibility and specificity of MRSAs isolated from various clinic samples with various methods including disc diffusion, SDS-PAGE and DNase test.

Immobilization of Coprinus plicatilis onto different carriers

Objectives: Bisphenol A (BP-A) is an essential component of polyvinyl chloride, polystyrene, phthalates and polycarbonate plastics linked by ester bonds, and it can leach out of plastics at high temperature, acid and basic medium. BP-A is known to have an endocrine disrupting effect and recent studies have started to link its levels as causative factors in many diseases such as diabetes, obesity, and other endocrine diseases. Kuwait is considered one of the hottest countries in the world, and measurements of BP-A levels due to leakage from plastics have never been reported from this Middle-Eastern country. This study measures the levels of BP-A in four randomly selected plastic toys and two plastic water bottles from two different companies after storage at 45 °C for four days. Methods: An ultra-pressure liquid chromatography coupled with an ultraviolet detector (UPLC-UV) analytical method was established to investigate BP-A levels in four of randomly chosen plastic toys (plastic tiger-plastic Lego blocks-plastic doll-small dolls) stored at 45 °C for 4 days. BP-A was extracted with 1 L of water and samples were analyzed by UPLC-UV. Results: The limit of detection (LOD) and the limit of quantification (LOQ) of the established analytical method were equal to 0.4 ppb and 1 ppb, respectively. The analytical method was able to measure accurately and precisely traces of BP-A in all randomly selected toys. BP-A levels was239 ppb in plastic tiger, 30 ppb in plastic Lego, 4 ppb in plastic doll, 3 ppb in small dolls and 59 ppb in drinking bottled water. Conclusion: The importance of BP-A level in plastics analysis raised due to its health concerns. Heat is a major factor for bisphenol leakage from plastics. However, Kuwait is considered one of the hottest countries, where high level leakage of BP-A from plastic toys and plastic water bottles for drinking water could pose significant health risks. Surprisingly, BP-A was detected in all randomly selected plastic toys and one out of two randomly selected polyethylene terephthalate (PET) drinking bottled water. Therefore, imported mineral water should be filled in a glass container rather than plastics due to high climate temperature. Moreover, Toys manufacturers should use BP-A free plastics or clearly specify storage conditions of their plastic products in order to prevent potential health risks resulting from BP-A leakage.A selective and sensitive liquid chromatography tandem mass spectrometry method (LC-MS/MS) has been developed for determination of Hypophyllanthin (HPT) and Silibinin (SBN) in human plasma. Sertraline hydrochloride was used as the internal standard (IS). Sample preparation involved liquid–liquid extraction by tert butyl metyl ether. Chromatographic separation was carried out on a C8 column (3 μm, 3.0 x 50.0 mm) with isocratic elution using a mobile phase of water:acetonitrile (10:90 v/v) at a flow rate of 0.6 mL/min. The detection was performed by tandem mass spectrometry with multiple reactions monitoring mode via electrospray ionization source in positive ionization mode. Analysis was carried out within 2.0 min over a linear concentration range of 1.00 -1000 and 1.00 – 500 ng/mL for HPT and SBN, respectively, and the LLOQ was 1 ng/ml for both compounds. The method was validated according to FDA guidelines for bioanalytical method validation and satisfactory results were obtained. This validated method was successfully applied to a pharmacokinetic study enrolling 20 male volunteers administered a single oral dose of Heptex vegetable capsules.F lung maturity is estimated using the lecithin/sphingomyelin ratio (L/S ratio) in amniotic fluid and it is commonly measured with thin-layer chromatography (TLC). The TLC method is time consuming and technically difficult; however, it is widely used because there is no alternative. We evaluated a novel method for measuring the L/S ratio, which involves a tip-column with a cation-exchange resin and mass spectrometry. Phospholipids in the amniotic fluid were extracted using methanol and chloroform. Choline-containing phospholipids such as lecithin and sphingomyelin were purified by passing them through the tip-column. LC-MS/MS and MALDI-TOF were used to directly analyze the purified samples. The L/S ratio by mass spectrometry was calculated from the sum peak intensity of the six lecithin, and that of sphingomyelin 34:1. In 20 samples, the L/S ratio determined with TLC was significantly correlated with that obtained by LC-MS/MS and MALDI-TOF. There was a 100% concordance between the L/S ratio by TLC and that by LC-MS/MS (kappa value=1.0). The concordance between the L/S ratio by TLC and that by MALDI-TOF was also 100% (kappa value=1.0). Our method provides a faster, simpler, and more reliable assessment of fetal lung maturity. The L/S ratio measured by LC-MS/MS and MALDI-TOF offers a compelling alternative method to traditional TLC.

Immobilization of Lycinibacillus fusiformis B26 cells in different matrices for use in turquoise blue HFG decolourization

Abstract The decolourization of Turquoise Blue HFG by immobilized cells of Lysinibacillus fusiformis B26 was investigated. Cells of L. fusiformis B26 were immobilized by entrapment in agar and calcium alginate matrices and attached in pumice particles. The effects of operational conditions (e.g., agar concentrations, cell concentrations, temperature, and inoculum amount) on microbial decolourization by immobilized cells were investigated. The results revealed that alginate was proven to be the best as exhibiting maximum decolourization (69.62%), followed by agar (55.55%) at 40°C. Pumice particles were the poorest. Optimum conditions for agar matrix were found: concentration was 3%, cell amount was 0.5 g and temperature was 40°C (55.55%). Ca-alginate beads were loaded with 0.5, 1.0 and 2.0 g of wet cell pellets and the highest colour removal activity was observed with 2.0 g of cell pellet at 40°C for alginate beads. Also, 0.5 and 1.0 g of pumice particles that were loaded with 0.25 and 0.5 g of cell pellets respectively were used and the results were found very similar to each other.

Synthesis, Characterization, and Antibacterial Activity of Dithiophosphonates and Amidodithiophosphonates

GRAPHICAL ABSTRACT Abstract New dithiophosphonates [RPS2(OR1)]− (R1 = fenchyl and bornyl) and amidodithiophosphonates [RPS2(NHR2)]− (R2 = 2-benzyloxycyclohexyl and 1-(4-fluorophenyl)ethyl) have been synthesized by the reaction of (ArPS2)2 (Ar = p-MeO-C6H4) and (1R)-endo-(+)-fenchyl alcohol and (−)-borneol or the amines (1S,2S)-(+)-2-benzyloxycyclohexylamine and (R)-