Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Chain-Length Dependent and Synergistic Prebiotic Effects of Xylooligosaccharides and Xylan on the Fecal Microbiota of Mice in Vitro(Elsevier, 2025) Büyükkileci, Ali Oğuz; Güleç, Şükrü; Buyukkileci, Ali Oguz; 01. Izmir Institute of Technology; 03.08. Department of Food Engineering; 03. Faculty of EngineeringOligomeric and polymeric prebiotics differ in their structural complexity, which influences microbial accessibility and fermentation kinetics. This study investigated the microbial responses to xylooligosaccharides (XOS), xylan (XY), and their combinations in comparison with inulin (INU) using an in vitro model inoculated with BALB/c mice fecal microbiota. Temporal analyses over 48 h included substrate consumption, acid production, and changes in microbial diversity. XOS was rapidly fermented, yielding high acetate and lactate levels, whereas XY was utilized more slowly due to its polymeric structure. During XY fermentation, xylobiose (X2) and xylotriose (X3) accumulated transiently, suggesting a stepwise depolymerization and utilization mechanism. The XOS + XY mix showed enhanced prebiotic effect, producing the highest amount of acid (151.8 mmol/L) and notably promoted the simultaneous enrichment of Bifidobacterium (12.5-fold), Bacteroides (8.85-fold), and Lactobacillus (14.9-fold) species compared to individual treatments These findings demonstrate that coadministered XOS and XY highlights the potential for designing tailored prebiotic formulations to optimize microbiota modulation, with potential relevance for human health.Editorial Editorial: Advancing Biotechnology in Turkiye: a Dedication To All Women(Springer, 2025) Cadirci, Bilge Hilal; Büyükkileci, Ali Oğuz; Buyukkileci, Ali Oguz; Binay, Baris; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyArticle Citation - WoS: 3Citation - Scopus: 3An Ex Vivo Model for Evaluation of Prebiotic Activity of Xylan and Xylooligosaccharides(Elsevier, 2025) Güleç, Şükrü; Büyükkileci, Ali Oğuz; Buyukkileci, Ali Oguz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyEx vivo techniques can provide more physiologically significant insights into prebiotic activity and overcome some limitations of in vitro tests. In this study, an ex vivo model, formed of a large intestine of mice, was tested to assess the effects of the hydrocolloidal natural polymer, xylan (XY), and its hydrolysis product, xylooligosaccharides (XOS). XY and XOS were loaded separately into the cecum, proximal colon, and distal colon. Their utilization and short-chain fatty acid (SCFA) formation by the colonized microflora and levels of dominant phyla and key genera such as Bifidobacterium, Bacteroides, and Lactobacillus were followed. XY and XOS were metabolized in all sections, and SCFAs were released. The results suggest that the slower utilization of XY compared to XOS in the cecum can enable this polysaccharide to move towards distal parts of the large intestine and extend the sites of prebiotic activity. Unlike widely used in vitro models, the ex vivo model allowed testing the utilization pattern and effects of the prebiotics in the natural environment of the microflora and examining the intestinal sections separately.Article Citation - WoS: 3Citation - Scopus: 3Development of Xylan-Coated Acid-Resistant Micellar Drug Carriers for Colon-Targeted Oral Delivery(Taylor & Francis As, 2024) Zeybek, Nuket; Büyükkileci, Ali Oğuz; Polat, Hurriyet; Polat, Hürriyet; Gulec, Sukru; Güleç, Şükrü; Buyukkileci, Ali Oguz; 03.08. Department of Food Engineering; 04.01. Department of Chemistry; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyOral delivery of hydrophobic drugs from the stomach through the colon has some requirements: (1) an acid-resistant carrier (2) a colon-specific drug release mechanism; and (3) an enhanced bioavailability. In this study, curcumin-loaded polymeric micelles with a xylan-based composite coating were designed and developed. For this purpose, a new synthesis method was used to precipitate xylan by concurrent chitosan polymerization at different xylan/chitosan ratios using a negatively charged crosslinking agent, TPP. The study was to provide the stability of the coated micellar structures in the stomach (low pH conditions) and their degradation in the colon (a natural environment of bacteria) to release the drug. It was observed that the coating successfully prevented early drug release up to 85%, depending on the fraction of xylan in the coating. The nanocarriers that first passed through the stomach conditions were incubated with a xylanolytic colonic bacterium (Bacteroides ovatus) to determine the bacterium-related release mechanism, which was around 27%. This shows the colon-specific release expectation of coated nanocarriers in the colon environment, with an additional benefit due to the degradation of xylan and an improvement in the colon environment by prebiotic activity.Article Citation - WoS: 10Citation - Scopus: 11Enzymatic Hydrolysis of Organosolv-Pretreated Corncob and Succinic Acid Production by Actinobacillus Succinogenes(Elsevier, 2024) Büyükkileci, Ali Oğuz; Buyukkileci, Ali Oguz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, the conversion of organosolv-treated corncob into monosaccharides through enzymatic sacchari-fication was investigated, with the resulting monosaccharides being utilized as a carbon source to produce succinic acid. The synergy between the cellulase and xylanase provided 76% cellulose and 64% xylan di-gestibility at 50 degrees C and pH 5.2. In separate hydrolysis and fermentation (SHF), Actinobacillus succinogenes pro-duced 12.7 g/L of succinic acid from the hydrolysate with 0.12 g/g yield based on the pretreated corncob. Simultaneous saccharification and fermentation (SSF) demonstrated better performance with 16 g/L succinic acid titer and 0.24 g/g yield, though SHF provided a higher production rate. The condition in the SSF (37 degrees C and pH near neutral) was suboptimal for the enzymes, thus the succinic acid production was limited by the saccharification step. These findings emphasize the potential of organosolv-treated corncob to serve as an enzymatic hydrolysis substrate without neutralization and detoxification, supplying glucose and xylose for succinic acid production by A. succinogenes.Article Citation - WoS: 5Citation - Scopus: 5The Potential of Walnut Shells for Production of Oligosaccharides by Liquid Hot Water Treatment(Springer Heidelberg, 2023) Surek, Ece; Büyükkileci, Ali Oğuz; Buyukkileci, Ali Oguz; 03.08. Department of Food Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyWalnut shell (WS), which is discarded in a large amount, is usually utilized for heating purposes; therefore, obtaining fuctional products can add value to this waste biomass. In this study, xylan was determined as the dominant carbohydrate (18.6% of dry weight) in WS. The potential applicability of liquid hot water (LHW) treatment to WS was investigated in order to solubilize hemicellulose and hydrolyze it into oligomers such as xylooligosaccharide (XOS) as a prebiotic oligosaccharide and recover solid and liquid fractions, which can be raw materials for other value-added products. LHW was applied at different temperatures (170-210 degrees C) for various times (15-120 min), and their effect was combined calculating severity factor (log R-o = 3.39-4.74). The solubilization of biomass was increased (up to 60.9%) with severity. Under optimum conditions (log R-o of 3.95, 190 degrees C-15 min), 81.5% of xylan was hydrolyzed and recovered as mainly XOS (69.8% of xylan), and also xylose and arabinose. The total oligosaccharide (XOS, arabino, gluco- and galacto-oligosaccharides) and monosaccharide (mainly xylose) concentration were 14.3 and 2 g/L, respectively, and by-products did not exceed 1.6 g/L. Moreover, 2.5 mg GAE/mL of total phenolics were obtained at those conditions, whereas that was raised to 3.4 mg GAE/mL at harsher conditions. This study presented that LHW treatment was an eco-friendly alternative method for valorization of WS through production of a liquid with high value-added compounds such as oligosaccharides and solid rich in cellulose and lignin.