Papers by Nevin Karaguler
Microalgae are highly diverse unicellular group which present in all existing earth ecosystems mo... more Microalgae are highly diverse unicellular group which present in all existing earth ecosystems mostly in ocean and freshwater. Schizochytrium sp. S31 is a marine thraustochytrid that contains oil rich in polyunsaturated fatty acids (PUFAs) especially ABSTRACT: Schizochytrium sp. is widely studied microalgae to obtain high content of polyunsaturated fatty acids (PUFAs) especially docosahexaenoic acid (22:6n-3) by cultivation optimization. In this study, cultivation and supercritical fluid lipid extraction conditions were optimized to maximize biomass and total lipid content of the Schizochytrium sp. S31, a known docosahexaenoic acid (DHA) producing marine algae by using response surface methodology. The traditional extraction methods have low extraction yields and use large amounts of toxic solvents. Supercritical fluid extraction (SFE) technique provide higher selectivity, shorter extraction times and do not use toxic organic solvents. Based on contour plots and canonical analysis, a maximum biomass production of 26.86g/L was obtained with 2.29 g/L monosodium glutamate (MSG), pH 5.8 cultivation conditions. Maximum lipid production of 35% was obtained with 0.49 g/L MSG at 17.6 °C temperature conditions. According to SFE results, pressure and temperature has significant effect (p <0.05) on total lipid yield and DHA concentration. It shows that, at constant temperature lipid yield and DHA concentration increases with higher pressure whereas decreases with higher temperature. After optimization of pressure, temperature and time variables of SFE, 30.2% lipid yield was obtained. In compare with traditional extraction, SFE has the advantages of to get solvent free value-added extracts.
Environmental Monitoring and Assessment, 2011
Small artificial lakes are ubiquitous in various natural environments. Small impoundments increas... more Small artificial lakes are ubiquitous in various natural environments. Small impoundments increase the residence time of water, thereby increasing the potential for retention of nutrients through biological and physical processes. We examined bacterial community structure of Lake Maslak, a small freshwater impoundment located in a densely populated region. The objective of our study was to investigate bacterial communities of the lake sediment which has not been determined and to elucidate the factors controlling bacterial diversity and the biogeochemical processes within the lake. For these purposes, surface water, lake bed sediments, and one core sample were collected. Microbiological characteristic of the lake bed and core sediments was determined by denaturing gradient gel electrophoresis targeting the 16S rRNA gene. Along with the microbiological studies, physicochemical (O 2 , pH, temperature) and geochemical properties of the surface (NO 3
Microbiology Resource Announcements, 2020
The thermophilic microorganism Geobacillus thermoleovorans ARTRW1 was isolated from water samples... more The thermophilic microorganism Geobacillus thermoleovorans ARTRW1 was isolated from water samples collected in the Armutlu hot spring in Turkey. Here, the whole-genome sequence and its annotations are reported. ABSTRACT The thermophilic microorganism Geobacillus thermoleovorans ARTRW1 was isolated from water samples collected in the Armutlu hot spring in Turkey. Here, the whole-genome sequence and its annotations are reported.
Characteristics of silver-containing titanium-based coating after thermal oxidation
Surface Innovations
OMICS: A Journal of Integrative Biology
Thermophilic microorganisms that thrive in extreme environments are of great importance because t... more Thermophilic microorganisms that thrive in extreme environments are of great importance because they express heat-resistant enzymes with the potential to serve as biocatalysts in industrial applications. Thermal proteome profiling (TPP) is a multiplexed quantitative mass spectrometry method for analyses of structural information and melting behavior of thousands of proteins, simultaneously determining the thermal denaturation profiles of each protein. We report, in this study, TPP applied to a thermophilic bacterial proteome, a recently isolated strain of Geobacillus thermoleovorans named as ARTRW1. The proteome was investigated in terms of thermostable enzymes that are relevant to industrial applications. In this study, we present the thermostability profiles of its 868 proteins. The majority of G. thermoleovorans proteome was observed to melt between 62.5°C and 72°C, with melting point (T m) mean value of 68.1°C-6.6°C. Unfolding characteristics of several enzymes, including amylase, protease, and lipase, were demonstrated which are highly informative in terms of their applicability to specific industrial processes. A significant correlation was observed between protein melting temperature and the structural features such as molecular weight and abundance, whereas correlations were modest or weak in relation to the a-helix structure percentages. Taken together, we demonstrated a system-wide melting profile analysis of a thermal proteome and listed proteins with elevated T m values that are highly promising for applications in medicine, food engineering, and cosmetics in particular. The extracted T m values were found similar to those obtained by biophysical methods applied to purified proteins. TPP analysis has significant industrial and biomedical potentials to accelerate thermophilic enzyme research and innovation.
Recombinant production and characterization of a novel esterase from a hypersaline lake, Acıgöl, by metagenomic approach
Extremophiles
MRS Proceedings
Proteins, one of the building blocks in organisms, not only control the assembly in biological sy... more Proteins, one of the building blocks in organisms, not only control the assembly in biological systems but also provide most of their complex functions. It may be possible to assemble materials for practical technological applications utilizing the unique advantages provided by proteins. Here we discuss molecular biomimetic pathways in the quest for imitating biology at the molecular scale via protein engineering. We use combinatorial biology protocols to select short polypeptides that have affinity to inorganic materials and use them in assembling novel hybrid materials. We give an overview of some of the recent developments of molecular engineering towards this goal. Inorganic surface specific proteins were identified by using cell surface and phage display technologies. Examples of metal and metal oxide specific polypeptides were represented with an emphasis on certain level of specificities. The recognition and self assembling characteristics of these inorganic-binding proteins ...
New Journal of Chemistry
AqpZ reconstituted proteoliposomes integrated into polyamide matrix using different ultrafiltrati... more AqpZ reconstituted proteoliposomes integrated into polyamide matrix using different ultrafiltration support membranes successfully with a performance increase of 12 times.
Optimisation of micro-arc oxidation electrolyte for fabrication of antibacterial coating on titanium
Materials Technology
Characterization of Aquaporin Z Incorporated Proteoliposomes with Quartz Crystal Microbalance with Dissipation (QCM-D)
Surface Innovations
Determination of the effect of proteoliposome concentration on Aquaporin Z incorporated nanofiltration membranes
Environmental Technology
Türkiye Jeoloji Bülteni / Geological Bulletin of Turkey
Characteristics of multi-layer coatings synthesized on Ti6Al4V alloy by micro-arc oxidation in silver nitrate added electrolytes
Surface and Coatings Technology, 2016
Febs Letters, Sep 1, 2009
The folding mechanism and stability of dimeric formate dehydrogenase from Candida methylica was a... more The folding mechanism and stability of dimeric formate dehydrogenase from Candida methylica was analysed by exposure to denaturing agents and to heat. Equilibrium denaturation data yielded a dissociation constant of about 10 À13 M for assembly of the protein from unfolded chains and the kinetics of refolding and unfolding revealed that the overall process comprises two steps. In the first step a marginally stable folded monomeric state is formed at a rate (k 1) of about 2 Â 10 À3 s À1 (by deduction k À1 is about10 À4 s À1) and assembles into the active dimeric state with a bimolecular rate constant (k 2) of about 2 Â 10 4 M À1 s À1. The rate of dissociation of the dimeric state in physiological conditions is extremely slow (k À2 $ 3 Â 10 À7 s À1).
Semi-Rational Design of Geobacillus stearothermophilus L-Lactate Dehydrogenase to Access Various Chiral α-Hydroxy Acids
Applied biochemistry and biotechnology, Jan 6, 2016
Chiral α-hydroxy acids (AHAs) are rapidly becoming important synthetic building blocks, in partic... more Chiral α-hydroxy acids (AHAs) are rapidly becoming important synthetic building blocks, in particular for the production of pharmaceuticals and other fine chemicals. Chiral compounds of a variety of functionalities are now often derived using enzymes, and L-lactate dehydrogenase from the thermophilic organism Geobacillus stearothermophilus (bsLDH) has the potential to be employed for the industrial synthesis of chiral α-hydroxy acids. Despite the thorough characterization of this enzyme, generation of variants with high activity on non-natural substrates has remained difficult and therefore limits the use of bsLDH in industry. Here, we present the engineering of bsLDH using semi-rational design as a method of focusing screening in a small and smart library for novel biocatalysts. In this study, six mutant libraries were designed in an effort to expand the substrate range of bsLDH. The eight variants identified as having enhanced activity toward the selected α-keto acids belonged to ...
Construction and expression of a bi-functional peptide by using genetic engineering methods for b
Microbial communities of Hyper saline Lake Salda and Acigol, SW Turkey and Their effects on Biogeochemical cycles
The modern lakes Acigol and Salda, located in the ``Lake District'' of SW of Turkey, are ... more The modern lakes Acigol and Salda, located in the ``Lake District'' of SW of Turkey, are known for the precipitation of sodium, magnesium, and potassium salts, and Mg-rich carbonate, respectively. As an analogue to extraterrestrial environments, these lakes provide opportunities to study microbe-mineral interactions in extreme environments, and in turn to better understand biogeochemical conditions in such environments. Lake Salda is an evaporatic alkaline lake (pH: 9) that covers an area of about 45 km2 in a partially serpentinized ophiolitic rocks. Water samples collected from the surface contain c. 295 mg/L Mg and c. 190 mg/L Na at a pH of 9.1, while the stream entering the lake (pH range 7-9.5) had values of 55 mg/L and 3 mg/L, respectively, indicating significant Na enrichment relative to Mg in the lake. Microbiological analyses of sediment samples from the stream and the lake indicate a diverse microbial community. Lake Acigol is a perennial lake with a maximum salinit...
Uploads
Papers by Nevin Karaguler