Onur Kırtel

Onur Kırtel
Technical University of Denmark | DTU · Novo Nordisk Foundation Center for Biosustainability

PhD

About

24
Publications
16,764
Reads
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175
Citations
Introduction
Onur Kırtel currently works at the Enzyme Engineering & Structural Biology Research Group of The Novo Nordisk Foundation Center for Biosustainability.
Additional affiliations
February 2018 - July 2018
KU Leuven
Position
  • Erasmus+ Visiting Student
September 2015 - August 2021
Marmara University
Position
  • PhD Student
September 2013 - July 2015
Ege University
Position
  • Master's Student
Description
  • Production of levan from molasses by Zymomonas mobilis
Education
September 2015 - August 2021
Marmara University
Field of study
  • Bioengineering
September 2013 - July 2015
Ege University
Field of study
  • Food Biotechnology
September 2008 - July 2013
Ege University
Field of study
  • Food Engineering

Publications

Publications (24)
Article
Fructans are multifunctional fructose-based water soluble carbohydrates found in all biological kingdoms but not in animals. Most research has focused on plant- and microbial fructans and has received a growing interest because of their practical applications. Nevertheless, the origin of fructan production, the so-called ‘fructan syndrome’, is stil...
Article
Saline and hypersaline environments make up the largest ecosystem on earth and the organisms living in such water-restricted environments have developed unique ways to cope with high salinity. As such these organisms not only carry significant industrial potential in a world where freshwater supplies are rapidly diminishing, but they also shed ligh...
Article
Full-text available
Fructans, homopolymers of fructose produced by fructosyltransferases (FTs), are emerging as intriguing components in halophiles since they are thought to be associated with osmotic stress tolerance and overall fitness of microorganisms and plants under high-salinity conditions. Here, we report on the full characterization of the first halophilic FT...
Article
Fructans are fructose-based oligo- and polysaccharides derived from sucrose that occur in a plethora of Eubacteria and plants. While fructan-producing (fructanogenic) Eubacteria are abundant in hypersaline environments, fructan production by Archaea has never been reported before. Exopolysaccharides accumulated by various Archaea from the Halobacte...
Article
Full-text available
Fructans are fructose-based (poly)saccharides with inulin and levan being the best-known ones. Thanks to their health-related benefits, inulin-type fructans have been under the focus of scientific and industrial communities, though mostly represented by plant-based inulins, and rarely by microbial ones. Recently, it was discovered that some extreme...
Article
Full-text available
A new exopolysaccharide (EPS) producing Gram-positive bacterium was isolated from the rhizosphere of Bouteloua dactyloides (buffalo grass) and its EPS product was structurally characterized. The isolate, designated as LB1-1A, was identified as Bacillus paralicheniformis based on 16S rRNA gene sequence and phylogenetic tree analysis. The EPS produce...
Article
Halomonas smyrnensis AAD6T is a moderately halophilic bacterium proven to be a powerful biotechnological tool with its ability to accumulate valuable biopolymers such as levan and poly(3-hydroxybutyrate) (PHB). Levan is a fructose homopolymer with β-2,6 fructofuranosidic linkages on the polymer backbone, and its distinctive applications in various...
Article
Fructansucrases (FSs), including inulosucrase (IS) and levansucrase (LS), are the members of the Glycoside Hydrolase family 68 (GH68) enzymes. IS and LS catalyze the polymerization of the fructosyl moiety from sucrose to inulin- and levan-type fructans, respectively. Lactobacillus-derived FSs have relatively extended N- and C-terminal sequences. Ho...
Article
Aims: Isolating a novel bacterial source of fructan from a saltern and analysis of its genome to better understand the possible roles of fructans in hypersaline environments. Methods and results: Bacteria were isolated from crude salt samples originating from Çamaltı Saltern in Western Turkey and screened for fructanogenic traits in high-salt an...
Chapter
Polysaccharides generated by microorganisms display structural diversity in terms of monosaccharide structure and organization, molecular weight, and branch design. This diversity facilitates their use in a plethora of food, health, biomedical, pharmaceutical, and cosmeceutical applications. Besides some of the well-known and industrially popular m...
Chapter
Fructans are fructose-based oligo- and polysaccharides synthesized using sucrose as substrate. Depending on the glycosidic bonds in their structure, they are classified as inulin and levan types or a mixture of these, namely graminans and agavins. Fructans constitute one of the most widespread functional biomolecules in nature and they occur in mic...
Chapter
Fructans are homopolymers of fructose that are widely synthesized by many Eubacteria and flowering plants in nature. They function as important parts of biofilms in microorganisms, and as storage carbohydrates or immune system mediators in plants. Both main types of fructans, levans and inulins, have found themselves a plethora of applications in f...
Chapter
Pathogenesis of microorganisms mostly relies on quorum sensing, a plethora of population density-dependent chemical signaling molecules. Plants interact with pathogenic and symbiotic microorganisms via the recognition of microbe-associated molecular patterns (MAMPs) such as chitin, lipopolysaccharides or fructans but they can also detect bacterial...
Article
Full-text available
Levan polysaccharide is an industrially important natural polymer with unique properties and diverse high-value applications. However, current bottlenecks associated with its large-scale production need to be overcome by innovative approaches leading to economically viable processes. Besides many mesophilic levan producers, halophilic Halomonas smy...
Poster
Levan ((2→6)-β-ᴅ-Fructofuranan) is a homopolymer of fructose produced by various bacteria, plants and some fungi. It is a unique polysaccharide considering its physicochemical characteristics such as low intrinsic viscosity, solubility in oil and water and strong adhesiveness. As a biocompatible polymer, it demonstrates anti-carcinogenic, anti-oxid...
Poster
Natural and functional food ingredients as dietary fibers gained escalating popularity due to increasing number of conscious consumers [1]. These indigestible functional ingredients not only improves product quality but also have many features like shelf life extension, reducing product deterioration and waste prevention in industrial perspective....
Poster
Halomonas levan temelli fonksyionel gıda bileşenlerinin geliştirilmesi
Presentation
Full-text available
Levansucrases are enzymes that catalyze the formation of levan, a fructan with β-2,6 linkages on its backbone, or fructooligosaccharides (FOS) via transfructosylation activity. Levan and FOS have tremendous potential of applications in various fields such as chemical, health and food industries. Enzymes produced by halophilic microorganisms are usu...
Poster
Levan ((2→6)-β-ᴅ-Fructofuranan) is a natural homopolysaccharide of fructose which has exceptional potential for food, chemical, pharmaceutical and medical industries. A moderately halophilic bacterium, Halomonas smyrnensis AAD6T, has been isolated from a saltern in Turkey and reported as the first levan-producing extremophile. It has been shown tha...

Questions

Questions (2)
Question
I am trying to determine the composition of some microbial polysaccharides I have purified. Prior to TLC and HPLC, I want to try this qualitative method known as potassium ferricyanide reducing power test, a.k.a Perkins test, which includes reacting hydrolyzed polysaccharide solutions with an alkaline solution K3[Fe(CN)6]. Briefly, reducing sugars such as glucose and fructose provide greenish-yellow color for different times in this test, so they can be distinguished.
My question is; can I use K4[Fe(CN)6] instead of K3[Fe(CN)6]?
Question
I've encountered different schools of thought about that matter. Some researchers claim that covering the mouth of an erlenmeyer flask with cotton + aluminum foil will reduce the oxygen transfer to the fermentation medium, so they use only cotton to seal the flask. Others use cotton + aluminum foil to reduce the risk of contamination. I am just curious about which one of the above two most researchers prefer when they carry out an aerobic fermentation.

Projects

Project (1)
Archived project
Functional foods have gained escalating importance on both scientific and commercial platforms due to the increasing demand of the health-conscious consumers. In food industry, fructans have the largest market share among the natural functional food additives. Especially inulin and inulin-type fructans stand out as the best known and widely used natural fructan additives due to their well established prebiotic, anticancer, antioxidant, antipathogenic and immunostimulatory activities. On the other hand, levan-type fructans are being consumed as functional food in various cultures and are mainly associated with high value food applications such as increasing the shelf life of food, bread quality and dough rheology, as edible food packaging and antipathogenic sweetener. In particular, several recent reports point to the superiority of levan-type fructans when compared to inulin-type fructans and hence there has been an elevated interest in developing levan-based functional food additives.