Person: TOKSOY ÖNER, EBRU
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TOKSOY ÖNER
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Publication Metadata only Fructan oligosaccharide priming alters apoplastic sugar dynamics and improves resistance against Botrytis cinerea in chicory(2022-06-24) TOKSOY ÖNER, EBRU; Versluys M., TOKSOY ÖNER E., Van den Ende W.Carbohydrates such as fructans can be involved in priming or defence stimulation, and hence potentially provide new strategies for crop protection against biotic stress. Chicory (Cichorium intybus) is a model plant for fructan research and is a crop with many known health benefits. Using the chicory–Botrytis cinerea pathosystem, we tested the effectiveness of fructan-induced immunity, focussing on different plant and microbial fructans. Sugar dynamics were followed after priming and subsequent pathogen infection. Our results indicated that many higher plants might detect extracellular levan oligosaccharides (LOS) of microbial origin, while chicory also detects extracellular small inulin-type fructooligosaccharides (FOS) of endogenous origin, thus differing from the findings of previous fructan priming studies. No clear positive effects were observed for inulin or mixed-type fructans. An elicitor-specific burst of reactive oxygen species was observed for sulfated LOS, while FOS and LOS both behaved as genuine priming agents. In addition, a direct antifungal effect was observed for sulfated LOS. Intriguingly, LOS priming led to a temporary increase in apoplastic sugar concentrations, mainly glucose, which could trigger downstream responses. Total sugar and starch contents in total extracts of LOS-primed leaves were higher after leaf detachment, indicating they could maintain their metabolic activity. Our results indicate the importance of balancing intra- and extracellular sugar levels (osmotic balance) in the context of ‘sweet immunity’ pathways.Publication Metadata only The book of fructans(Elsevier Science, Oxford/Amsterdam , 2023-03-01) TOKSOY ÖNER, EBRU; Toksoy Öner E. (Editör), Van Den Ende W. (Editör)After more than 30 years, The Book of Fructans represents the first and most comprehensive coverage of fructans generated by pioneer glycoscientists from the field. It outlines the fundamentals of all fructan types, their terminology, chemical and structural-functional features, biosynthetic enzymes that make and break them, their presence and possible roles in nature, their evolutionary aspects and their microbial, enzymatic, and plant-based production. Additional sections cover the applications of fructans, specifically, the agro/chemical and biomedical applications, health, pharmaceutical and cosmetic applications, fructans in food and feed, fructan nanotechnology, the immunomodulatory and antiviral effects of fructans and the perspectives for fructans in circular economies and sustainable societies. Intended for scientists, entrepreneurs, academicians and students working in related fields, this book will be a useful resource for all who wish to learn more about these extraordinary carbohydrates.Publication Open Access Genomic analysis provides new Insights into biotechnological and industrial potential of parageobacillus thermantarcticus M1(2022-06-01) KASAVİ, CEYDA; TOKSOY ÖNER, EBRU; YILDIZ S. Y., Finore I., Leone L., Romano I., Lama L., KASAVİ C., Nicolaus B., TOKSOY ÖNER E., Poli A.Parageobacillus thermantarcticus strain M1 is a Gram-positive, motile, facultative anaerobic, spore forming, and thermophilic bacterium, isolated from geothermal soil of the crater of Mount Melbourne (74 degrees 22 \" S, 164 degrees 40 \" E) during the Italian Antarctic Expedition occurred in Austral summer 1986-1987. Strain M1 demonstrated great biotechnological and industrial potential owing to its ability to produce exopolysaccharides (EPSs), ethanol and thermostable extracellular enzymes, such as an xylanase and a beta-xylosidase, and intracellular ones, such as xylose/glucose isomerase and protease. Furthermore, recent studies revealed its high potential in green chemistry due to its use in residual biomass transformation/valorization and as an appropriate model for microbial astrobiology studies. In the present study, using a systems-based approach, genomic analysis of P. thermantarcticus M1 was carried out to enlighten its functional characteristics. The elucidation of whole-genome organization of this thermophilic cell factory increased our understanding of biological mechanisms and pathways, by providing valuable information on the essential genes related to the biosynthesis of nucleotide sugar precursors, monosaccharide unit assembly, as well as the production of EPSs and ethanol. In addition, gene prediction and genome annotation studies identified genes encoding xylanolytic enzymes that are required for the conversion of lignocellulosic materials to high-value added molecules. Our findings pointed out the significant potential of strain M1 in various biotechnological and industrial applications considering its capacity to produce EPSs, ethanol and thermostable enzymes via the utilization of lignocellulosic waste materials.Publication Open Access Protein surface engineering and interaction studies of maltogenic amylase towards improved enzyme immobilisation(2022-07-01) TOKSOY ÖNER, EBRU; Jaafar N. R., Jailani N., Rahman R. A., TOKSOY ÖNER E., Murad A. M. A., Illias R. M.A combined strategy of computational, protein engineering and cross-linked enzyme aggregates (CLEAs) approaches was performed on Bacillus lehensis G1 maltogenic amylase (Mag1) to investigate the preferred amino acids and orientation of the cross-linker in constructing stable and efficient biocatalyst. From the computational analysis, Mag1 exhibited the highest binding affinity towards chitosan (-7.5 kcal/mol) and favours having interactions with aspartic acid whereas glutaraldehyde was the least favoured (-3.4 kcal/mol) and has preferences for lysine. A total of eight Mag1 variants were constructed with either Asp or Lys substitutions on different secondary structures surface. Mutant Mag1-mDh exhibited the highest recovery activity (82.3%) in comparison to other Mag1 variants. Mutants-CLEAs exhibited higher thermal stability (20-30% activity) at 80 C whilst Mag1-CLEAs could only retain 9% of activity at the same temperature. Reusability analysis revealed that mutants-CLEAs can be recovered up to 8 cycles whereas Mag1-CLEAs activity could only be retained for up to 6 cycles. Thus, it is evident that amino acids on the enzyme\"s surface play a crucial role in the construction of highly stable, efficient and recyclable CLEAs. This demonstrates the necessity to determine the preferential amino acid by the cross-linkers in advance to facilitate CLEAs immobilisation for designing efficient biocatalysts.Publication Open Access Co-production of levan with other high-value bioproducts: A review(2023-04-30) TOKSOY ÖNER, EBRU; de Siqueira E. C., TOKSOY ÖNER E.Levan is a homopolysaccharide of fructose that has both scientific and industrial importance, with various applications in health, pharmaceutical, cosmetic and food industries. Despite its broad spectrum of uses, there are only a limited number of commercial levan sources due to the high costs related to its production. To make production economically viable, efforts have been concentrated on the selection of levan-producing microorganisms, the genetic manipulation of new strains, and the use of inexpensive agro-industrial byproducts as substrates. Another efficient strategy involves the concomitant synthesis of other products with high market value and as such, the successful co-production of levan was demonstrated with fructooligosaccharides, ethanol, sorbitol, poly-ε-lysine, poly-γ-glutamic acid and polyhydroxyalkanoates. This paper offers a systematic review of important aspects regarding recent strategies involving the simultaneous synthesis of levan and other bioproducts of aggregate value reported to date and discusses the challenges and opportunities for its large-scale production and applications.Publication Open Access Production of a high molecular weight levan by Bacillus paralicheniformis, an industrially and agriculturally important isolate from the buffalo grass rhizosphere(2022-09-01) TOKSOY ÖNER, EBRU; Nasir A., Ahmad W., Sattar F., Ashfaq I., Lindemann S. R., Chen M., Van den Ende W., TOKSOY ÖNER E., Kirtel O., Khaliq S., et al.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 produced by LB1-1A was identified as a levan, having beta(2 -> 6) linked backbone with beta(2 -> 1) linkages at the branch points (4.66%). The isolate LB1-1A yielded large amount (similar to 42 g/l) of levan having high weight average molecular weight (Mw) of 5.517 x10(7) Da. The relatively low degree of branching and high molecular weight of this levan makes B. paralicheniformis LB1-1A a promising candidate for industrial applications.Publication Open Access Understanding the effects of chitosan, chia mucilage, levan based composite coatings on the shelf life of sweet cherry(2023-08-01) TOKSOY ÖNER, EBRU; Mujtaba M., Ali Q., Yilmaz B. A., Seckin Kurubas M., Ustun H., ERKAN M., Kaya M., Cicek M., Oner E. T.Sweet cherry (Prunus avium L.) fruits are prone to quality and quantity loss in shelf-life conditions and cold storage due to their short post-harvest life. Until now efforts have been made to extend the shelf life of the sweet cherry. However, an efficient and commercially scalable process remains elusive. To contribute to this challenge, here in this study, biobased composite coatings consisting of chitosan, mucilage, and levan, were applied on sweet cherry fruits and tested for postharvest parameters in both market and cold storage conditions. Results demonstrated that the shelf life of sweet cherries can be extended until the 30th day while retaining important post-harvest properties like decreased weight loss, fungal deterioration, increased stem removal force, total flavonoid, L-ascorbic acid, and oxalic acid. Given the cost-effectiveness of the polymers used, the findings of this study indicate the feasibility of extending the shelf-life of sweet cherries on a larger scale.