Nur Koçberber Kılıç

Proteomic changes in response to chromium(VI) toxicity in Pseudomonas aeruginosa.

A proteomic approach was used to identify proteins involved in Cr(VI) stress response of Pseudomonas aeruginosa to toxic Cr(VI). Cytosolic and membrane fractions from bacteria exposed to 300 mg l(-1) Cr(VI) were prepared, 2D gel electrophoresis in combination with MALDI-TOF MS and LC-MS/MS was used to identify proteins whose expression level increased or decreased upon exposure to Cr(VI). Overexpressed proteins include stress proteins, proteins involved in protein biosynthesis, proteins responsible for energy production, proteins involved in free radicals detoxification by the glutathione system, outer membrane proteins, MucD, while downregulated proteins were isocitrate dehydrogenase and 30S ribosomal protein S1. Under Cr(VI) exposure, upregulation of MucD (role in exopolysaccharide production) and outer membrane proteins concluded that bacteria have access to more than one resistance mechanism against toxic metal ions. We propose that the mechanisms of Cr(VI) resistance include production of exopolysaccharide and complexing of metal ions outside the cell.

Stimulation of reactive dye removal by cyanobacteria in media containing triacontanol hormone

In this study, Reactive Red, Remazol Blue, and Reactive Black B removal capacities of Synechocystis sp. and Phormidium sp. were investigated. The microorganisms were cultivated in 100ml BG 11 medium and incubated at 30 degrees C under continuous illumination (12.5 wm(-2) (2400 lx)) for 20 days in plant growth chamber. Trials were carried out at pH 9.5 for Reactive Red, pH 8.5 for Remazol Blue and Reactive Black B removal in media without and with triacontanol (TRIA). Removal capacities of Synechocystis sp. and Phormidium sp. were found higher in media containing TRIA. So that, Synechocystis sp. and Phormidium sp. removed Reactive Red with 25.7% and 35.4%, Remazol Blue with 37.5% and 25.5%, and Reactive Black B with 29.2% and 28.3% yield at 25 mg l(-1) dye concentrations, respectively. There is no report investigating dye removal by Synechocystis sp. and removal of pollutants in media including TRIA hormone. Our data indicated the cyanobacteria tested in this study were suitable for effective treatment processes of such wastewaters including reactive dyes, and their removal capacity could be increased by TRIA, through stimulation of the biomass production.

Triacontanol hormone stimulates population, growth and Brilliant Blue R dye removal by common duckweed from culture media

This work is focussed on assessing the potentialities of Lemna minor (L.) for the treatment of reactive dyes polluted wastewaters and investigating the possibility of bioremoval performance stimulation by adding triacontanol hormone to the cultures. In the vast literature describing removal of reactive dyes, considering the lack of reports using of common duckweed in wastewater treatment apparently due to the inadequate efficiency. In the present study, the experiments showed that 1 mg l(-1) triacontanol stimulated duckweed growth. The effect of different dye types (Reactive Orange 14, Reactive Red 120, Reactive Black 5, Brilliant Blue R, and Reactive Brilliant Blue R) onto duckweed growth was tested. Plants grew at most in media with Brilliant Blue R. The highest biomass, in terms of frond number (87+/-1.5) were accompanied with 59.6% maximum dye removal were found in samples containing 2.5 mg l(-1) initial Brilliant Blue R and 1 mg l(-1) triacontanol, indicating hormonal stimulation of both activities. The results presented here that L. minor (L.) could be used effectively to treat wastewaters containing dye.

Evaluation of hydrogen production by Clostridium strains on beet molasses

Clostridium acetobutylicum DSM 792, C. acetobutylicum DSM 1731 and two newly isolated bacteria defined as the members of genus Clostridium – based on the 16S rRNA analysis and biochemical traits – were characterized with regard to their hydrogen production in media containing increasing beet molasses concentrations. The highest hydrogen yield was observed for C. acetobutylicum DSM 792 with a yield of 2.8 mol H2 mol−1 hexose in medium including 60 g L−1 molasses. This bacterium also produced the maximum amount of hydrogen (5908.8 mL L−1) at the same molasses concentration. A slightly lower hydrogen yield was measured for C. acetobutylicum DSM 1731 (2.5 mol H2 mol−1 hexose) when grown on 40 g L−1 molasses. The new isolates Clostridium roseum C and Clostridium saccharoperbutylacetonicum PF produced hydrogen with yields of 2.0 mol H2 mol−1 hexose at 40 and 60 g L−1 molasses and 2.1 mol H2 mol−1 hexose at 40 g L−1 molasses, respectively.

Green Synthesis of Silver Nanoparticles Using Cyanobacteria and Evaluation of their Photocatalytic and Antimicrobial Activity

Nowadays, green and efficient synthetic strategies have been gaining great interest for the synthesis of nanoparticles. In this study, the biosynthesis of silver nanoparticles and its photocatalytic activity for photodegradation of organic dye and antimicrobial property was studied. The initial syntheses of Ag nanoparticles were characterized by UV–Vis spectrophotometer and showed the surface plasmon resonance band at 430-450 nm. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) study showed evidence that proteins are possible reducing agents. The structure of AgNPs was determined by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). SEM and TEM studies revealed the synthesized AgNPs to be spherical. The AgNPs exhibited photocatalytic activity for photodegradation of organic dye such as Methylene Blue. Approximately 18% degradations of methylene blue within 4 h was observed with biosynthesized Ag nanoparticles in the photocatalytic degradation process.

EPS production and bioremoval of heavy metals by mixed and pure bacterial cultures isolated from Ankara Stream

This study is focused on isolation of Ni(II), Cu(II) and Cr(VI) resistant bacteria to assess their exopolysaccharide (EPS) production and related bioremoval capacities. Mixed cultures had higher heavy metal removal capacity in media with molasses (MAS) than the control cultures lacking this carbon (AS) containing 50 mg/l of heavy metal. The yields were 32%, 75.7%, and 51.1% in MAS, while the corresponding values were 29%, 55.1%, and 34.5% in AS, respectively. Purification of the strains 1, 5 and 6 present in the mixed cultures decreased the bioremoval capacities of the mixed culture samples, although these strains produced higher EPS amounts in MAS agar. Strain 5 had the highest Cu(II) (69.1%) and Cr(VI) (43.1%) removal rates at 25 mg/l initial concentration of each pollutant with EPS amounts of 0.74 g/l and 1.05 g/l, respectively. This strain was identified as Stenotrophomonas maltophilia. The presented data show that especially mixed and also pure cultures of bacterial strains isolated from Ankara Stream could be assessed as potential bioremoval agents in the treatment of Cu(II) or Cr(VI) containing wastewaters.

Phenol biodegradation by different mixed cultures and the optimization of efficiency of the degradation

In this study, the phenol degradation capacities of four different mixed cultures, namely, Ankara Stream (AS), petroleum-contaminated soil (PS), olive mill wastewater (OMW), and drug mill wastewater (DMW) were investigated with regards to different pH levels, phenol (497.2–1183.0 mg/L) and biomass concentrations (0.5–3.0%(v/v)). The most efficient culture was selected and the optimal conditions required for its highest performance in phenol degradation were studied. We found 100% phenol degradation for DMW at nearly 1000 mg/L initial concentration. The optimum pH was 8 and the mixed culture could tolerate phenol levels up to approximately 1500 mg/L. The selected culture degraded all of the phenol concentrations ranging from 497.2 to 1183.0 mg/L with 100% efficiency after 48 h and 120 h incubation, respectively. Increasing the biomass concentration from 0.5% to 3.0% (v/v) level decreased the incubation time needed for complete degradation. The data indicate that the mixed culture used in this study can be taken as a good candidate for effective treatment of waters contaminated by phenol.

Bioremoval of Reactive Blue 220 by Gonium sp. biomass

Gonium sp. was tested for the bioremoval of Reactive Blue 220 (RB220) dye at different conditions such as pH values, initial dye concentrations and biomass concentrations to evaluate the possibility of using this microalga in treating wastewaters. According to the data obtained from the experiments, microalgae removed RB220 with the highest yield (54.2%) at pH 8, and could treat the applied dye with the highest removal percentage as 84.2% at the lowest dye concentration (26.2 mg/L RB220). Increasing Gonium sp. biomass concentration from 0.21 to 0.53 g/L stimulated RB220 removal rate from 87.7% to 96.8%. The present study clearly indicated that Gonium sp. biomass could be used as a bioremediation biosorbent in treating RB220 dye in the related wastewaters.

Dual bioremediation of phenol and Cr(VI) by mixed microbial cultures in the presence of molasses

Simultaneous phenol and Cr(VI) bioremoval by two different mixed cultures, from petroleum-contaminated soil (PS) and boron-contaminated wastewater (BW), was investigated in regard to different culture media, pH levels (6-8), initial phenol (25-100 mg/L) and Cr(VI) (15-50 mg/L) concentrations. The optimum medium was found to be mineral salt medium tested, which contained 1% (v/v) molasses (MSM). Optimum pH values were 6 for PS and 8 for BW. All of the phenol present in the samples was mineralized regardless of its concentrations tested, Cr(VI) bioremoval was enhanced by the increase in phenol concentrations, and molasses also exerted a positive effect on Cr(VI) removal, and the yields reached 100% for both pollutants, even at 13.1 mg/L Cr(VI) and 91.1 mg/L phenol concentration in PS samples. In MSM containing PS samples approximate efficiency was 100% for phenol removal; but Cr(VI) removal ratios were 64.9% and 41.7% at 25.8 mg/L and 41.3 mg/L concentrations, respectively. Finally it can be concluded that molasses stimulated Cr(VI) bioremoval at elevated phenolic conditions in the mixed microbial culture, and molasses might be of use for the bioremediation of phenol and Cr(VI) polluted wastewaters.