Aydın Akbulut

Immobilization of tyrosinase on modified diatom biosilica: Enzymatic removal of phenolic compounds from aqueous solution

Acid and plasma treated diatom-biosilica particles, were modified with 3-aminopropyl triethoxysilane (APTES), and activated with glutaraldehyde. Then, tyrosinase was immobilized onto the pre-activated biosilica by covalent bonding. The biosilica properties were determined using SEM, and FTIR. The enzyme system has been characterized as a function of pH, temperature and substrate concentration. Optimum pH of the free and immobilized enzyme was found to be pH 7.0. Optimum temperatures of the free and immobilized enzymes were determined as 35 and 45 °C respectively. The biodegradation of phenolic compounds (i.e., phenol, para-cresol and phenyl acetate) has been studied by means of immobilized tyrosinase in a batch system. The immobilized tyrosinase retained about 74% of its original activity after 10 times repeated use in the batch system. Moreover, the storage stability of the tyrosinase-biosilica system resulted excellent, since they maintained more than 67% of the initial activity after eighth week storage. Highly porous structure of biosilica can provide large surface area for immobilization of high quantity enzyme. The porous structure of the biosilica can decrease diffusion limitation both substrate phenols and their products. Finally, the immobilized tyrosinase was used in a batch system for degradation of three different phenols.

Fourier transform infrared (FTIR) spectroscopy for identification of Chlorella vulgaris Beijerinck 1890 and Scenedesmus obliquus (Turpin) Kützing 1833

Fourier transform infrared (FTIR) spectroscopy was used in this study to identify and determine spectral features of Chlorella vulgaris Beijerinck 1890 and Scenedesmus obliquus (Turpin) Kutzing 1833. Two cultures were grown in a chemically-defined media under photoautotrophic culture conditions isolated from eutrophic freshwater lake in Ankara. For FTIR analyses, a view from the transmission region between 4000 and 500 cm -1 on the microscope was chosen. All FTIR spectra showed a closely similar sequence of 11 distinct bands and were assigned a range of vibrationally active chemical groups, including residual water (–OH), lipid (–CH2), cellulose (–C=O), protein (amide), nucleic acid (>P=O) and starch (–C–O). The nonparametric (Spearman) correlations revealed a high level of correlations between certain bands. Comparison of band intensities (normalized to amide I) using Mann-Whitney test demonstrated major differences in relative band intensities, with bands 1, 3 and 5 to 11 showing significant differences between the two algal species at the 99% significant level. While bands 8, 9 and 10 showed the highest variations (CV>30%) in C. vulgaris, bands 1, 2, 3 and 7 with the highest variations (CV>30%) in S. obliquus. The results show that FTIR technique has the potential to become applicable for the determination of single cell biomass composition from phytoplankton communities.

Distribution and status of the medicinal leech (Hirudo medicinalis L.) in Turkey

A survey of all the major potential habitats in western Turkey showed that medicinal leeches, Hirudo medicinalis L., are widely distributed over the country and are not rare. They occur in practically all suitable habitats and the only region where they were found to be absent is that of the large river deltas in the south of the country (Çukurova deltas, Göksu delta). There may be zoogeographic reasons for this (Taurus mountains barrier). The application of a semi-quantitative survey method using collecting efficiency (number of leeches collected per hour by a single person) allowed a rapid assessment to be made of its status in a large number of wetlands. Leech density varied considerably from wetland to wetland, and the results enabled a ranking of the Turkish wetlands to be made according to their importance for medicinal leeches. Taking both the leech density and the size of leech habitats into account, the largest populations were identified on the Black Sea coast (Kizilirmak delta, Yeşilirmak delta and Karagöl Marshes near Sinop) and in inner and south-west Anatolia (Eber Gölü, Karamik and Sultan Marshes). Commercial exploitation for the pharmaceutical industry and for other purposes takes place at only a few places and does not appear to affect the population seriously. However, many populations are threatened by the draining of their habitats.

Chapter 17 – Rivers of Turkey

Publisher Summary Geologically, Turkey is a part of the Alpine belt that extends from the Atlantic Ocean to the Himalayan Mountains. This belt started to form in the early Tertiary when the Arabian, African, and Indian plates collided with the Eurasian plate. Since the late Tertiary, Turkey has been moving toward the Eurasian plate whose resistance splits Turkey along a northwest direction, forming east west extending horst-graben structures in the west. The geomorphologic evolution of Turkey includes pre- and post-Miocene phases that constrained the paleo- and neotectonic phases. The Central Anatolian Plateau owes its present morphology mainly to erosional processes before the Miocene, whereas the rest of the country continues to evolve by ongoing uplift processes. The evolution of river basins and development of major river valleys are a result of these geological processes. Turkey, because of its complex geologic, geomorphic, and climatic settings, has many rivers that enter the surrounding seas and neighboring countries of Iraq, Iran, and Armenia. Overall, 26 main drainage basins, including 4 endorheic basins lacking an outflow to the sea, occur in Turkey. This chapter focuses on 16 catchments, although the Terek and Kura Rivers are covered only marginally because of limited available information. It also briefly describes the endorheic basins and presents the general characterization of the Turkish river basins.

The study of heavy metal pollution and accumulation in water, sediment, and fish tissue in Kızılırmak River Basin in Turkey

The accumulation of heavy metals such as Pb, Hg, Co, Cr, Cu, Zn, and Br were determined in water, sediment, muscle, and gill of three fish species (Leuciscus cephalus, Capoetatinca, Capoeta capoeta) which were collected in Kızılırmak River Basin (Delice River). The metal concentration showed a general trend of Br>Zn> Pb>Cr>Cu>Hg>Co in water and Cr>Zn>Pb> Cu>Co>Hg>Br in sediment samples while Zn> Cu>Pb>Br>Cr>Hg>Co were in muscle and Zn>Pb>Cu>Cr>Br>Hg>Co were in the gill tissue.

Aminopyridine modified Spirulina platensis biomass for chromium (VI) adsorption in aqueous solution

Chemical modification of Spirulina platensis biomass was realized by sequential treatment of algal surface with epichlorohydrin and aminopyridine. Adsorptive properties of Cr(VI) ions on native and aminopyridine modified algal biomass were investigated by varying pH, contact time, ionic strength, initial Cr(VI) concentration, and temperature. FTIR and analytical analysis indicated that carboxyl and amino groups were the major functional groups for Cr(VI) ions adsorption. The optimum adsorption was observed at pH 3.0 for native and modified algal biomasses. The adsorption capacity was found to be 79.6 and 158.7 mg g(-1), for native and modified algal biomasses, respectively. For continuous system studies, the experiments were conducted to study the effect of important design parameters such as flow rate and initial concentration of metal ions, and the maximum sorption capacity was observed at a flow rate of 50 mL h(-1), and Cr(VI) ions concentration 200 mg L(-1) with modified biomass. Experimental data fitted a pseudo-second-order equation. The regeneration performance was observed to be 89.6% and 94.3% for native and modified algal biomass, respectively.

The plankton composition of Lake Mogan in Central Anatolia

Abstract The trophic status of Lake Mogan a shallow, alluvial lake in Central Anatolia, was assessed during a nine-month survey in 1994, including community structure and seasonal distribution of planktonic organisms. Bacillariophyta were dominant among the phytoplankton, followed by Chlorophyta, Cyanophyta, Cryptophyta, Euglenophyta and Dinophyta. Among the zooplankton, Arctodiaptomus bacillifer, Diaphanosoma lacustris and Keratella quadrata were the dominant species. Rotifers were most abundant in spring, Cladocera in summer and copepods in autumn. A rapid increase in zooplankton density correlated with a rise in temperature of 8°C and an increase in the chlorophyll concentration during summer. A total of 21 species of Rotifera, 6 species of Cladocera and 2 species of Copepoda have been identified, in addition to 90 species (from 8 genera) of phytoplanktonic organisms.

A 2800-year multi-proxy sedimentary record of climate change from Lake Çubuk (Göynük, Bolu, NW Anatolia)

The sediment of Lake Çubuk in NW Anatolia, which is situated very close to the climate boundary between the dry Central Anatolia and the wet Marmara region, is regarded as a suitable climate archive to test inward and outward movements of this boundary in accordance with past climate variations. Herein, we study the stratigraphic record of the last 2800 years of this landslide-dammed lake at 1030 m elevation, using multi-proxy tools (sedimentology, major and trace element geochemistry, stable isotopes, pollen, diatoms and ostracods) and compare the results with other contemporaneous Anatolian climatic records. Our findings indicate that Lake Çubuk recorded seven distinct climatic periods in the last 2800 years that have been previously revealed elsewhere in Anatolia. The most arid period occurred at the end of the Near-East Aridification Phase at approximately 200 BC when the δ18O shifted to very negative values, and the planktonic diatom ratio considerably decreased. The Dark Ages and the late Byzantine periods between AD 670 and 1070 are characterized by more positive δ18O values, increasingly higher lake levels and the most extensive arboreal cover of the entire record. The ‘Little Ice Age’ appeared suddenly, within 40 years, at AD 1350 and is reflected in all of the proxies, including a positive shift in δ18O, a sharp decrease in pollen of shrub and herb to the benefit of pine trees and a rapid increase in benthic diatom abundance indicating a lake level shallowing. In many parts of the record, a close match between the stable isotopes and the pollen assemblage zones in the last 2800 years demonstrates that climate rather than human activity was the primary driver of vegetation cover in this mid-altitude mountain of NW Anatolia.