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Öğe Bifidogenic effect and in vitro immunomodulatory roles of melibiose-derived oligosaccharides produced by the acceptor reaction of glucansucrase E81(Elsevier Sci Ltd, 2020) Ispirli, Humeyra; Kaya, Yasemin; Dertli, EnesGlucansucrases are responsible for the production of alpha-glucans using sucrose as the substrate. Glucansucrases may also produce different oligosaccharides by transferring the glucose moiety from sucrose to a variety carbohydrates acting as acceptor nucleophile. In this study, melibiose-derived oligosaccharides were produced by the glucansucrase from Lactobacillus reuteri E81 expressed without the N-terminal region (GtfA-Delta N). The reaction products were characterized by TLC, LC-MS and NMR analysis and it was found that GtfA-Delta N synthesized melibiose-derived oligosaccharides (DP3 and DP4) by adding glucose units through alpha 1- > 3 or 1- > 6 glycosidic bond. The functional characteristics of these melibiose-derived oligosaccharides were determined by testing the immune-modulatory functions in HT-29 cells and testing their growth promoting effects for important probiotic and pathogenic strains. The melibiose-derived oligosaccharides triggered the production of anti-inflammatory cytokine IL-10 and pro-inflammatory cytokine TNF-alpha depending on their concentrations. Finally, melibiose-derived oligosaccharides showed bifidogenic effect as potential prebiotics.Öğe Bioactive and technological properties of an ?-D-glucan synthesized by Weissella cibaria PDER21(Elsevier Sci Ltd, 2022) Yilmaz, Mustafa Tahsin; Ispirli, Humeyra; Taylan, Osman; Alamoudi, Mohammed; Dertli, EnesA slimy-mucinous-type colony of EPS-producing Weissella cibaria PDER21 was isolated and identified. The monomer composition was glucose, showing that the EPS is a glucan type homopolysaccharide, The core structure of (1 -> 6)-linked alpha-D-glucose units including (1 -> 3)-linked alpha-D-glucose branches at a ratio of 93.4/6.6 was revealed by H-1 and C-13 NMR spectra and confirmed by FTIR analysis. The glucan showed a superior thermal stability with almost no degradation in structure up to 300 degrees C. XRD analysis revealed the amorphous structure while SEM analysis confirmed the layer-like morphology. The glucan had an antioxidant activity (89.5%), water-holding capacity (103.7%) and water solubility index (80.7%) values, suggesting that the glucan had a strong level of antioxidant properties; good water binding capacity and excellent solubility. The glucan PDER21 is a polysaccharide possessing a good combination of technical and functional attributes, suggesting a great deal of potential for use in the food industry.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 and immune-modulatory roles of branched glucan and acetylated gluco-oligosaccharides produced by glucansucrase 40 from Leuconostoc mesenteroides YTU 40(Nature Portfolio, 2025) Dere, Sevda; Ispirli, Humeyra; Korkmaz, Kader; Tuncil, Yunus Emre; Sagdic, Osman; Narbad, Arjan; Dertli, EnesGlucansucrases (GS) are functional enzymes for the production of distinct glucan and gluco-oligosaccharide structures with potential bioactive characteristics. In this study, an active glucansucrase (GS40) was identified within the genome of Leuconostoc mesenteroides YTU 40 that was further cloned, heterologously expressed and biochemically characterised. GS40 was capable of production of a branched dextran with similar to 20% (1 -> 3)-alpha-D-Glc residues detected by(1)H and(13)C NMR analysis. Acceptor reactions of GS40 with maltose and cellobiose were performed and distinct maltose/cellobiose derivative acetylated gluco-oligosaccharides were produced detected by TLC, NMR and LC-MS analysis. The bioactive characteristics of branched dextran and gluco-oligosaccharides were tested by determination of their immune-modulatory roles in terms of triggering IL-12, IL-10, IL-4 and TNF-alpha cytokine levels. These findings can be important to unveil the role of glucansucrases for the production of gluco-oligosaccharides that can be used as functional ingredients for food and other industries.Öğe Characterization and in situ bioprotective efficacy of reuterin E81 produced by Limosilactobacillus reuteri E81 in white cheese model(Elsevier, 2025) Ispirli, Humeyra; Ozturk, Hale Inci; Dertli, EnesThis study focused on characterization and in situ application of reuterin E81, a potent antimicrobial compound produced by Limosilactobacillus (L.) reuteri E81, in white cheese. Strain E81 harbored the gene island containing pdu-cbi-cob-hem clusters responsible for reuterin production and this led to investigation of reuterin production for this strain. Initially, reuterin was synthesized from glycerol and characterized using NMR and FT-MIR analyses. Specific 1H and 13C NMR peaks confirmed the presence of reuterin components such as 3-hydroxypropionaldehyde and acrolein, while FT-MIR spectra indicated a distinct carbonyl (C=O) stretching band at 1717 cm-1, characteristic of aldehyde groups of reuterin system. Reuterin E81 showed dose dependent fungistatic and bactericidal effects, with complete inhibition of Gram-negative ones at lower doses. In white cheese production, four groups were prepared, including control and experimental groups with or without glycerol addition. The challenge test conducted over 30 days of cold storage demonstrated that white cheese samples containing L. reuteri E81 and glycerol achieved a significant reduction in microbial loads, with Escherichia (E.) coli counts decreasing from 6.4 log CFU/g to undetectable levels, which was attributed to in situ reuterin production. Meanwhile, total aerobic mesophilic bacterial counts declined progressively. These findings highlight the potential of in situ reuterin production as a natural strategy to enhance the microbiological safety of white cheese. However, it also inhibited the growth of S. thermophilus and L. reuteri cultures. The inhibitory effects of reuterin on beneficial lactic acid bacteria suggest the need for further optimization to balance food safety with starter culture viability.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 Characterization of Bee Bread Produced with Defined Starter Cultures Mimicking the Natural Fermentation Process(Mdpi, 2023) Poyraz, Fatmanur; Yalmanci, Dilara; Ispirli, Humeyra; Dertli, EnesBee bread is a product with unique properties for humans and bees that is produced through the fermentation of pollen in the honeycomb, mainly caused by lactic acid bacteria (LAB) and yeast strains present in the environment. It is a rich source of nutrients such as proteins, polyphenols and vitamins. Despite the potential nutritional value of bee bread, it is consumed at low levels, as harvesting bee bread from the hives is costly and difficult. This study aimed to produce a standard bee bread by using different strains of the fructophilic lactic acid bacteria (FLAB) Lactobacillus kunkeei and the yeasts Starmeralla magnolia MP-2 and Zygosaccharomyces siamensis MP-14, previously isolated from bee products. In this context, bee bread was produced from pollen by solid-state fermentation using selected FLAB and yeast species, which were then compared with spontaneously developed and commercially available bee bread in terms of microbial stability, physicochemical properties, total phenolic component amounts, in vitro digestibility and amino acid profiles. As a result, it was determined that bee bread made from bee pollen fermented with starter cultures showed improved characteristics than commercial bee bread and was more advantageous in terms of absorption as well as production processes.Öğe Characterizations and In Vitro Gut Microbiome Modulatory Effects of Gluco-Oligosaccharides Synthesized by the Acceptor Reactions of Glucansucrase 53(Mdpi, 2025) Bayaman, Rabia Yusra; Alkay, Zuhal; Ispirli, Humeyra; Arioglu-Tuncil, Seda; Dere, Sevda; Can, Hasan; Dertli, EnesThe production of novel oligosaccharides with potential prebiotic effects is of interest to expand the current market and explore the effectiveness of new functional carbohydrate forms. The utilization of glucansucrases is a cost-effective and environmentally friendly biotechnological strategy for producing novel gluco-oligosaccharides through acceptor reactions. In this study, an active glucansucrase (GS53) was used to produce gluco-oligosaccharides via its acceptor reactions with glucose, maltose, and maltotriose, and these oligosaccharides were tested in terms of structure and their gut microbiome modulatory effects. The formations of oligosaccharides were monitored by TLC analysis, and GS53 was active for the three acceptors but not for the other sugars tested. The structural characterization of the gluco-oligosaccharides by 1H NMR analysis revealed the glycosylation of each acceptor with alpha-(1 -> 3) and alpha-(1 -> 6) linkages, whereas LC-MS analysis demonstrated the formations of DP 8, DP 7, and DP 6 oligosaccharides with acceptors maltose, maltotriose, and glucose, respectively. In vitro fecal fermentation analysis, in which microbial short-chain fatty acids (SCFAs) and microbial compositional changes were assessed using gas chromatography and 16S rRNA sequencing, respectively, demonstrated that the gluco-oligosaccharides formed SCFAs-particularly propionate and butyrate-at levels comparable to those observed with inulin, a well-established prebiotic. Additionally, the gluco-oligosaccharides were found to promote the growth of Bifidobacterium adolescentis and Blautia OTUs, which are known to have important physiological functions beneficial to human health. Overall, these results demonstrate that gluco-oligosaccharides synthesized using GS53 through acceptor reactions exhibit prebiotic potentials and could be utilized in the future as dietary supplements as well as in the development of functional foods targeting colonic health.Öğe Comparison of the probiotic characteristics of Lactic Acid Bacteria (LAB) isolated from sourdough and infant feces(Elsevier, 2022) Kaya, Yasemin; Erten, Tayyibe; Vurmaz, Melike; Ispirli, Humeyra; Simsek, Omer; Dertli, EnesProbiotics are beneficial microorganisms with certain characteristics such as survival under gastrointestinal conditions, adhesion to intestinal surface and different functions which result in several health benefits to host. With this regards, this study aimed to isolate Lactic Acid Bacteria (LAB) from sourdough and human feces as two different environments and to test their potential probiotic functions. In total nine distinct isolates were assessed with several probiotic functions such as in vitro adhesion to human colon cells, antimicrobial activities and survival under harsh gastrointestinal conditions. In general, distinct strains showed strong antimicrobial activity against the pathogenic and fungal strains tested in this study. Importantly, the adhesion levels to HT29 cells were determined between 0.29 % and 9.54% and Lactobacillus paracasei F7B showed the highest adhesion. All isolates tolerated the bile salt after 24 h and the infant feces isolates showed good survival characteristics at pH 4.Öğe Detection of fructophilic lactic acid bacteria (FLAB) in bee bread and bee pollen samples and determination of their functional roles(Wiley, 2021) Ispirli, Humeyra; Dertli, EnesIn this study, bee bread and bee pollen samples were characterized in terms of presence of fructophilic lactic acid bacteria (FLAB). Following discrimination and identification of FLAB strains, their functional roles were determined. Genotypic characterization of FLAB strains revealed the presence of 27 distinct strains belonging to Lactobacillus kunkeei (21), Fructobacillus fructosus (3), Lactobacillus plantarum (2), and Leuconostoc mesenteroides (1) strains. In terms of functional roles, all FLAB strains demonstrated high levels of autoaggregation and hydrophobicity properties whereas L. kunkeei and F. fructosus strains did not tolerate bile salts and low pH conditions. A low level of antibiotic resistance was observed among FLAB strains and importantly FLAB strains demonstrated high levels of antibacterial and antifungal activities where strain specific properties played roles. The highest exopolysaccharide (EPS) production yields were obtained for L. kunkeei AP15, AP37 and L. mesenteroides AP-40 which produced 2.79, 2.01, and 5.37 g/L EPS, respectively. Practical applications Bee bread and bee pollen are among beneficial bee products produced and consumed in all over the world. Production of bee bread relies on the fermentation process of bee pollen where a special LAB group FLAB plays roles. Despite the increment of the importance of these products for human consumption, there is a lack of knowledge for the microbial composition of these products. In this study, FLAB strains were isolated and identified from bee bread and bee pollen samples, and their technofunctional role was determined. The FLAB strains would be evaluated as starter cultures for production of bee products under industrial conditions.Öğe Determination of functional characteristics, presence of virulence factors and antibiotic resistance of enterococci isolated from Turkish White-Cheese(Elsevier Science Bv, 2016) Akin, Nihat; Dertli, Enes; Ispirli, Humeyra; Yuvasen, Ayse; Akaya, Zuhal[Abstract Not Available]Öğe Determining the optimum model parameters for oligosaccharide production efficiency using response surface integrated particle swarm optimization method: an experimental validation study(Taylor & Francis Inc, 2020) Sensoy, Abdullah Tahir; Ispirli, Humeyra; Dertli, EnesGlucansucrases (GTFs) catalyzes the synthesis of alpha-glucans from sucrose and oligosaccharides in the presence of an acceptor sugar by transferring glucosyl units to the acceptor molecule with different linkages. The acceptor reactions can be affected by several parameters and this study aimed to determine the optimal reaction parameters for the production of glucansucrase-based oligosaccharides using sucrose and maltose as the donor and acceptor sugars, respectively via a hybrid technique of Response Surface Method (RSM) and Particle Swarm Optimization (PSO). The experimental design was performed using Central Composite Design and the tested parameters were enzyme concentration, acceptor:donor ratio and the reaction period. The optimization studies showed that enzyme concentration was the most effective parameter for the final oligosaccharides yields. The optimal values of the significant parameters determined for enzyme concentration and acceptor:donor ratio were 3.45 U and 0.62, respectively. Even the response surface plots for input parameters verified the PSO results, an experimental validation study was performed for the reverification. The experimental verification results obtained were also consistent with the PSO results. These findings will help our understanding in the role of different parameters for the production of oligosaccharides in the acceptor reactions of GTFs.Öğe Development and characterization of postbiotic-enriched biodegradable films with antifungal activity for tomato storage(Wiley, 2025) Kaya, Yasemin; Ispirli, Humeyra; Bozkurt, Fatih; Sagdic, Osman; Sengul, Mustafa; Dertli, EnesBACKGROUND One of the major contributors to postharvest losses in tomatoes is the development of infectious mold diseases. In this study, four distinct biodegradable film formulations were developed incorporating postbiotics derived from Lactiplantibacillus plantarum Y48 and the polysaccharide alternan. The formulations included alternan, sodium alginate and glycerol (AAG), alternan, postbiotic, sodium alginate and glycerol (APAG), postbiotic, sodium alginate and glycerol (PAG), and sodium alginate and glycerol (AG) as a control. The films were characterized in terms of their physical, mechanical, thermal, and morphological properties. To assess antifungal efficacy, tomatoes artificially inoculated with Alternaria alternata were coated with each film and stored at ambient temperature for 8 days.RESULTS The incorporation of alternan and postbiotics enhanced both the mechanical strength and thermal stability of the films. Fourier-transform infrared (FTIR) analysis confirmed the successful integration of the bioactive components into the polymer matrix. Scanning electron microscopy (SEM) imaging revealed that postbiotic addition contributed to a rougher and more rigid surface morphology, while alternan improved the structural cohesion of the films. All film formulations exhibited significant inhibitory effects against A. alternata, with the PAG formulation demonstrating the most pronounced antifungal activity.CONCLUSION These results suggest that the PAG film, enriched with postbiotics, represents a promising biocontrol strategy for mitigating fungal spoilage in tomatoes. In conclusion, this study underscores the potential of combining postbiotics and alternan for the development of active, biodegradable edible films with antifungal functionality for postharvest preservation. (c) 2025 Society of Chemical Industry.Öğe Diversity and functional characteristics of lactic acid bacteria from traditional kefir grains(Wiley, 2020) Purutoglu, Kubra; Ispirli, Humeyra; Yuzer, Mustafa Onur; Serencam, Huseyin; Dertli, EnesTraditional kefir grains were collected from distinct parts of Turkey, and their microbial profile was determined. A wide bacterial biota was observed formed by distinct lactic acid bacteria (LAB) in which Lactococcus lactis strains appeared to be dominant. Yeast species were also identified in kefir grains. Significant levels of antifungal and antibacterial activities were monitored in kefir isolates. All tested LAB produced an exopolysaccharide (EPS) containing glucose and galactose, and some strains formed a fructan-type EPS. Importantly, low levels of antibiotic resistance were observed among the kefir isolates.Öğe The effect of flours of different immature cereal grains on sourdough and sourdough bread: Microbiological, rheological, textural and sugar profiles(Wiley, 2022) Alkay, Zuhal; Yilmaz, Mustafa Tahsin; Can, Asli Muslu; Ispirli, Humeyra; Dertli, EnesIn this study, the utilization of LAB (Lactiplantibacillus plantarum, Levilactobacillus brevis, Furfurilactobacillus rossiae, Weissella cibaria) cultures with selected flours of different immature cereal grains (wheat, barley, oat and rye) on sourdough and sourdough bread was investigated. In total, 16 different sourdough breads were produced and microbiological, pH, TTA and rheological properties of sourdoughs at 0, 8 and 24 h were determined. At the beginning of the fermentation, while sourdoughs showed elasticity, they showed viscoelastic properties after 24 h of fermentation. The sugar profile of cereal grains at the stage of milk formation and the sugar groups presented in EPSs isolated from sourdoughs were revealed by HPLC analysis. The sugar groups in sourdoughs were glucose, xylose and arabinose, while the sugars in the immature cereal grains were glucose, fructose and mannose. The highest EPS production level (1882.69 +/- 8.16) was observed in immature barley flour and Lpb. plantarum containing sourdough and all sourdoughs were found to contain glucan type EPSs. It was observed that the amount of EPS produced by the related species differed significantly under different grain conditions. Besides, it was observed that the sourdough breads produced were harder than the control bread. Novelty Impact Statement Wheat, barley, oat and rye immature grains and four distinct LAB strains were used during sourdough fermentation. Immature grain type and LAB strain used were determinants for in situ exopolysaccharide (EPS) production. Viscoelastic properties of sourdough and textural properties of sourdough bread were affected by grains and LAB strain utilized.Öğe Facile biomimetic synthesis of AgNPs using aqueous extract of Helichrysum arenarium: characterization and antimicrobial activity(Taylor & Francis Inc, 2022) Yilmaz, Mustafa Tahsin; Ispirli, Humeyra; Taylan, Osman; Balubaid, Mohammad; Dertli, EnesThe present study focuses on synthesis of silver nanoparticles (AgNPs) by employment of a green and facile synthesis method. Aqueous extract of Helichrysum arenarium was used as a reducing and capping agent. The bioreduction of silver particles was monitored using UV-Vis spectroscopy based on increase in color intensity led by surface plasmon resonance. SEM, TEM, FTIR, DSC, and XRD analyses were followed for characterization, divulging that the nanoparticles were thermally resistant in the size of approximately 20 nm with a quasi-spherical shape without any agglomeration. AgNPs possessed a nanocrystal form with presence of crystalline Ag. EDAX analysis was used to verify that the nanoparticles were silver as revealed by a typical optical absorption peak of metallic silver nanocrystallites. The AgNPs were shown to have strong antibacterial and antifungal effects on some foodborne pathogens. The method developed in this study could offer a green, facile biomimetic, and cost-effective method.Öğe A green nano-biosynthesis of selenium nanoparticles with Tarragon extract: Structural, thermal, and antimicrobial characterization(Elsevier, 2021) Yilmaz, Mustafa Tahsin; Ispirli, Humeyra; Taylan, Osman; Dertli, EnesIn this study, tarragon extract was used as a reducing agent to perform green nano-biosynthesis of selenium nanoparticles (SeNPs). The synthesized SeNPs were characterized using measurements of UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy disperse analysis of X rays (EDAX), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD) and differential scanning analysis (DSC). Synthesis of nanoparticles was confirmed by observing a peak at 212 nm in UV-VIS, indicating the surface plasmon resonance of SeNPs. Tarragon extract enabled a stable dispersion of SeNPs, giving rise to formation of the nanoparticles in the shape of quasi-spheres without clustering with the sizes between 20 and 50 nm. The SeNPs were shown to be in the form of nanocrystals, having Se embedded in the nanostructure with high thermal stability (a high resistance to thermal process over 200 degrees C). The SeNPs synthesized with tarragon extract could remarkably increase the inhibition zones from approximately 13 to 18 mm against the pathogenic bacteria and from 10 to 14 mm, 17-36 mm, 8-12 mm, 15-24.5 mm and 9-14 mm, against A. alternata, A. niger, A. parasiticus, B. cinerea, F. oxysporum and P. chrysogenum, respectively.Öğe Identification of Lactic Acid Bacteria (LAB) from pre-fermented liquids of selected cereals and legumes and characterization of their exopolysaccharides (EPS)(Elsevier, 2022) Yalmanci, Dilara; Ispirli, Humeyra; Dertli, EnesRecently, isolation of Lactic Acid Bacteria (LAB) strains with important technological functions from plant-based products has gained special interests related with the increment of consumer preferences to the plant-based fermented products. In this context, various cereals and legumes that were underwent to germination or not were selected for the isolation of exopolysaccharide (EPS) producer LAB strains in this study. Following geno-typic discrimination, 17 distinct strains belonging to Weissella confusa, Weissella cibaria, Lactococcus lactis subsp. hordniae, Leuconostoc lactis, Lactiplantibacillus plantarum and Leuconostoc mesenteroides were identified from pre -ferment liquids. Two strains Weissella confusa W-16 and Leuconostoc lactis GW-6 were the highest EPS producers, and their EPSs were further characterized. The 1H and 13C NMR results revealed that both strains were dextran producers containing (1 -> 3)-linked alpha-D-glucose units as branches with 9.2% and 6.9% levels for Weissella confusa W-16 and Leuconostoc lactis GW-6, respectively. FTIR analysis also supported the dextran structure and demonstrated the functional groups within the dextrans. A high level of thermal stability was observed in both dextrans detected by TGA and DSC analysis. Both dextrans were in amorphous characteristics determined by XRD analysis. These findings demonstrate that pre-fermented liquids of different cereals and legumes can be source of technologically important LAB strains with EPS production characteristics.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.
