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Öğe Biosynthesis of alternan-stabilized selenium nanoparticles: A study on characterization and applications for antibacterial and antifungal purposes(Taylor & Francis Inc, 2024) ElObeid, Tahra; Yilmaz, Mustafa Tahsin; Ispirli, Humeyra; Sagdic, Osman; Taylan, Osman; Basahel, Abdulrahman; Karaboga, DervisIn this study, the alternan/selenium nanoparticles (Alt/SeNPs) were characterized with respect to their formation, morphology, size, selenium distribution, molecular, crystallographic, and thermal properties using UV-Vis spectroscopy, SEM, TEM, EDAX, FTIR, XRD, DSC and TGA measurements. UV-VIS measurements confirmed the synthesis of nanoparticles by observing a maximum surface plasmon resonance peak at 212 nm. In this study, alternan contributed to stabilizing the dispersion of SeNPs, resulting in a cluster of spherical and well-dispersed nanoparticles ranging in size from 50 to 90 nanometers. Nanoparticles were found to be highly thermally stable and in a nanocrystalline structure. The ABTS and CUPRAC radical scavenging activities of Alt/SeNPs were remarkable (95% and 78% at 4 and 6 mg/mL levels of Alt/SeNPs, respectively). Alt/SeNPs had also good inhibitory activities (3.5-4.0 and 4-15 mm of inhibition zone levels at 5 mg/mL level of Alt/against foodborne pathogenic bacteria and fungi, respectively).Öğe Characterisation and functional roles of a highly branched dextran produced by a bee pollen isolate Leuconostoc mesenteroides BI-20(Elsevier, 2022) Yilmaz, Mustafa Tahsin; Ispirli, Humeyra; Taylan, Osman; Tasdemir, Volkan; Sagdic, Osman; Dertli, EnesLactic Acid Bacteria (LAB) from different niches can be responsible for the production of distinct exopoly-saccharides (EPS) that might possess important structural and technological features. In this respect, the aim of this study was to isolate an EPS producer LAB strain from bee pollen environment. Leuconostoc mesenteroides BI-20 with a slimy-mucoid colony morphology was identified from bee pollen and the structural, technological and functional characteristics of EPS produced by this strain were determined. EPS BI-20 was a highly branched dextran containing 20% (1 -> 3)-linked alpha-D-glucose branches determined by H-1 and C-13 NMR analysis. The presence of (1 -> 6)/(1 -> 3)-linked alpha-D-glucose linkages in dextran BI-20 was also confirmed by FTIR analysis. Dextran BI-20, with a molecular weight of 1 x 10(8) Da, possessed strong thermal properties, amorphous nature and highly branched and fibrous microstructural characteristics determined by DSC, TGA, XRD and SEM analysis, respectively. In terms of functional roles, dextran BI-20 demonstrated strong antioxidant capacity detected by ABTS and CUPRAC tests. Finally, no digestion was observed in dextran BI-20 under simulated gastric conditions. Results of this study unveiled techno-functional characteristics of dextran BI-20 produced by a bee pollen isolate LAB strain.Öğe Characterization of a glucansucrase from Lactobacillus reuteri E81 and production of malto-oligosaccharides(Taylor & Francis Ltd, 2019) Ispirli, Humeyra; Yuzer, Mustafa Onur; Skory, Christopher; Colquhoun, Ian J.; Sagdic, Osman; Dertli, EnesGlucansucrases, which can be produced by different Lactic Acid Bacteria (LAB), catalyze the synthesis of alpha-glucans with different structures and properties using sucrose as substrate. In this study, a novel glucansucrase (GTFA) from Lactobacillus reuteri E81 was identified and heterologously expressed. Alignments of GTFA with other glucansucrases revealed its novelty and a putative 3D model structure was obtained. The biochemical properties of the truncated enzyme without the N-terminal variable region, GTFA-Delta N, was characterized. The K-m and V-max were found to be 7.5 mM and 1.49 IU/mg, respectively, and it showed optimum activities at pH 7 and at 50 degrees C. The GTFA-Delta N produced in vitro an alpha-glucan with (alpha 1 -> 3) and (alpha 1 -> 6) glycosidic linkages using sucrose as the substrate. Importantly, GTFA-Delta N synthesized DP = 9 oligosaccharides using sucrose and maltose as the donor and acceptor sugars, respectively, as detected by TLC, HPLC, LC-MS and NMR analysis.Öğe Impact of glucan type exopolysaccharide (EPS) production on technological characteristics of sourdough bread(Elsevier Sci Ltd, 2020) Ispirli, Humeyra; Ozmen, Duygu; Yilmaz, Mustafa Tahsin; Sagdic, Osman; Dertli, EnesIn this study, technological role of a-glucan with (alpha 1-3) and (alpha 1-6) glycosidic linkages produced by Lactobacillus reuteri E81 on sourdough rheology and bread texture was investigated. To achieve this, a glucan deficient Delta gtfA mutant was produced by the deletion of the glucansucrase gene from strain E81. By comparison of glucan-positive and glucan-negative strains for rheological properties of sourdough revealed that in situ a-glucan production resulted in higher elasticity in sourdough. However, no additional effect of in situ glucan on textural characteristics of bread was observed although addition of glucan ex situ at 0.09% level significantly decreased bread hardness. Scanning Electron Microscopy (SEM) images of lyophilized sourdoughs confirmed association of glucan and starch granules forming a film like structure in sourdough.Öğe An integrated neural-fuzzy methodology for characterisation and modelling of exopolysaccharide (EPS) production levels of Leuconostoc mesenteroides DL1(Pergamon-Elsevier Science Ltd, 2020) Kabli, Mohammad; Yilmaz, Mustafa Tahsin; Taylan, Osman; Kaya, Yasemin; Ispirli, Humeyra; Basahel, Abdulrahman; Sagdic, OsmanOptimisation of exopolysaccharides (EPS) production in Lactic Acid Bacteria (LAB) is an important task as EPS production can be affected by different parameters. In this respect, this study aimed to characterise the structure of an EPS from Leuconstoc mesenteroides DL1 strain and to optimise the EPS production by determination of the effects of incubation time, sucrose concentration, incubation temperature and initial levan concentration (input parameters) using integrated ANNs (Artificial neural networks) and fuzzy modelling approaches. The characterisation of the EPS monomeric composition by HPLC analysis revealed that EPS DL1 was composed of glucose and fructose. The H-1 and C-13 NMR spectra of EPS DL1 also confirmed the glucan and fructan production. The effects of the input parameters on glucan and fructan production levels as output parameters by DL1 were optimised using neural network and fuzzy modelling tools. The fuzzy model was developed based on the recognition of basic elements of input-output parameters, and the power of ANNs used for system identification. A structural analysis was carried out to improve the flexibility of fuzzy model, and to design the unknown mappings of the input and output parameters more robustly. The parameters then were fine-tuned by qualitative reasoning to establish the relations of input output parameters using membership functions (MFs) and their intervals determination. A hybrid training algorithm was employed for parameter identification, MFs and their interval determination to obtain the fuzzy model. The model can predict the outcome parameters; glucan and fructan with high accuracy for the predetermined input parameters.Öğe Physicochemical and structural characterisation of a branched dextran type exopolysaccharide (EPS) from Weissella confusa S6 isolated from fermented sausage (Sucuk)(Elsevier, 2024) Ozpinar, Fatma Beyza; Ispirli, Huemeyra; Kayacan, Selma; Korkmaz, Kader; Dere, Sevda; Sagdic, Osman; Alkay, ZuhalExopolysaccharide (EPS) producing Lactic Acid Bacteria (LAB) species can be presented in distinct environments. In this study, Turkish fermented sausage (sucuk) was tested for the presence of EPS producer LAB strains and slimy-mucoid colonies were selected for further tests. Among the isolates, Weissella confusa strain S6 was identified and tested for the physicochemical characterisation of its EPS. This strain was found to produce 0.74 g L-1 of EPS in modified BHI medium conditions. Structural characterisation of EPS S6 by 1H and 13C NMR demonstrated that EPS S6 was a highly branched dextran type glucan formed by mainly (1 -* 2)-linked alpha-D- glucose units together with low levels of (1 -* 3)-linked alpha-D-glucose units as branching points. This structure was further confirmed by methylation analysis detected by GC-MS. An average molecular weight of 8 x 106 Da was detected for dextran S6. The FTIR analysis supported the dextran structure and revealed the presence of distinct functional groups within dextran S6 structure. A strong thermal profile was observed for dextran S6 detected by DSC and TGA analysis and dextran S6 revealed a degradation temperature of 289 degrees C. In terms of physical status, dextran S6 showed amorphous nature detected by XRD analysis. SEM analysis of dextran S6 demonstrated its rough, compact and porous morphology whereas AFM analysis of dextran S6 detected in its water solution showed the irregularity with no clear cross -link within the dextran chains. These technological features of dextran S6 suggests its potential to be used for in situ or ex situ application during meat fermentations.Öğe Preparation of gentiobiose-derived oligosaccharides by glucansucrase E81 and determination of prebiotic and immune-modulatory functions(Elsevier Sci Ltd, 2019) Ispirli, Humeyra; Colquhoun, Ian J.; Sahin, Engin; Sagdic, Osman; Dertli, EnesGentiobiose-derived oligosaccharides were synthesized by the acceptor reaction of glucansucrase E81 obtained from Lactobacillus reuteri E81 with sucrose and gentiobiose as donor-acceptor sugars, respectively. The reaction products were monitored by TLC analysis and gentiobiose-derived oligosaccharides up to DP 8 were formed during the acceptor reaction as determined by ESI-MS/MS analysis. The glycosylation of the gentiobiose with alpha-(1 -> 6) linkages and alpha-(1 -> 3) linkages was shown by H-1 and C-13 NMR analysis confirming the structure of these gentiobiose-derived oligosaccharides. The in vitro prebiotic function of the oligosaccharides was determined in which probiotic strains were stimulated whereas no growth was observed in pathogen strains. Gentiobiosederived oligosaccharides showed immune-modulatory functions in vitro and triggered the production of IL-4, IL12 and TNF-alpha cytokines in HT29 cells in a dose dependent manner. This study showed the production and functional characterisation of gentiobiose-derived oligosaccharides establishing a promising avenue for future applications.Öğe Synthesis of silver nanoparticles prepared with a dextran-type exopolysaccharide fromWeissella cibariaMED17 with antimicrobial functions(Taylor & Francis Inc, 2021) Ispirli, Humeyra; Sagdic, Osman; Dertli, EnesMicrobial polysaccharides can find distinct applications as stabilizer agents including synthesis of nanoparticles. In this study, a dextran-type exopolysaccharide (EPS) was used as the stabilizer agent for the green synthesis of silver nanoparticles (AgNPs-Dex) with antimicrobial characteristics. UV-vis spectroscopy analysis was used to test the formation of AgNPs-Dex. The uniform morphology at around 10 nm size was observed for AgNPs-Dex by TEM analysis and importantly EDX analysis demonstrated the embedment of Ag(+)ions within dextran as the stabilizer agent. XRD analysis confirmed the crystalline nature of AgNPs-Dex and FTIR analysis demonstrated the interactions of dextran functional groups with silver. DSC and TGA analysis showed the alteration in the thermal stability of AgNPs-Dex compared to the stabilizer dextran. The antibacterial and antifungal activities of AgNPs-Dex were determined against food originated pathogenic bacteria and fungi and important inhibition levels were observed at 1 mg ml(-1)concentration of AgNPs-Dex and this activity was observed to be concentration dependent.Öğe Turkish royal jelly: amino acid, physicochemical, antioxidant, multi-elemental, antibacterial and fingerprint profiles by analytical techniques combined with chemometrics(Taylor & Francis Ltd, 2021) Ecem Bayram, Nesrin; Cebi, Nur; Celik, Saffet; Gercek, Yusuf Can; Bayram, Sinan; Tanugur Samanci, Asli Elif; Sagdic, OsmanRoyal jelly is one of the most remarkable commercial bee products used in cosmetics, medicine, and as a dietary supplement. This study aimed to determine some quality parameters (amino acid, multi-elemental, total phenolic-flavonoid, 10-HDA, sugar, and moisture content) as well as antioxidant and antimicrobial activities of different royal jelly samples (domestic and non-domestic samples). In this study, royal jelly samples exhibited high antioxidant and antimicrobial activity. 10-HDA values were found to be higher in domestic royal jelly samples (2.17-2.71%) compared to non-domestic samples (0.31-1.71%). Also, it was found that the acidity value varied between 2.57-3.37 mL 0.1 N NaOH/g and 3.87-4.97 mL 0.1 N NaOH/g in non-domestic and domestic royal jelly samples, respectively. L-Proline was the amino acid with the highest rate of occurrence in both domestic (21972.39-35053.00 nmol/g) and non-domestic (19688.31-21711.50 nmol/g) samples. It was determined that the new method developed for amino acid analysis has many advantages over other methods. Chemometrics of principal component analysis (PCA) showed that amino acid profile, elemental profile, and chemical parameters were capable of presenting characteristic and descriptive properties of royal jelly samples. In addition to these findings, Raman spectroscopy combined with chemometrics of hierarchical cluster analysis (HCA) was successfully used to distinguish domestic and non-domestic royal jelly samples. The obtained results will provide an important basis for subsequent research on the evaluation of the amino acid content, physicochemical properties, phenolic content, and the antioxidant and elemental profile of royal jelly.Öğe Utilisation of an active branching sucrase from Lactobacillus kunkeei AP-37 to produce techno-functional poly-oligosaccharides(Elsevier, 2023) Ispirli, Huemeyra; Korkmaz, Kader; Arioglu-Tuncil, Seda; Bozkurt, Fatih; Sagdic, Osman; Tuncil, Yunus Emre; Narbad, ArjanGlucansucrase AP-37 was extracted from the culture supernatant of Lactobacillus kunkeei AP-37 and character-istics of the glucan produced by the active glucansucrase in terms of structural and functional roles were determined in this study. A molecular weight around 300 kDa was observed for glucansucrase AP-37 and its acceptor reactions with maltose, melibiose and mannose were also conducted to unveil the prebiotic potential of the poly-oligosaccharides formed via these reactions. The core structure of glucan AP-37 was determined by 1H and 13C NMR and GC/MS analysis which revealed that glucan AP-37 was a highly branched dextran composing of high levels of (1-+ 3)-linked alpha-D-glucose units with low levels of (1-+ 2)-linked alpha-D-glucose units. The structural features of the glucan formed, demonstrated that glucansucrase AP-37 was an alpha-(1-+ 3) branching sucrase. Dextran AP-37 was further characterised by FTIR analysis and XRD analysis demonstrated its amorphous nature. A fibrous compact morphology was observed for dextran AP-37 with SEM analysis whereas TGA and DSC analysis revealed its high stability as no degradation was observed up to 312 degrees C. Finally, the prebiotic potential of the dextran AP-37 and the gluco-oligosaccharides produced with the acceptor reaction of alpha-(1-+ 3) branching sucrase AP-37 were determined and promising results were found for the gluco-oligosaccharides to act as prebiotics.
