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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, Enes
A 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.
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, Dervis
In 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).
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, Enes
Lactic 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.
Characterisation of dextran AP-27 produced by bee pollen isolate Lactobacillus kunkeei AP-27
(Elsevier Sci Ltd, 2023) Yilmaz, Mustafa T.; Ispirli, Huemeyra; Alidrisi, Hassan; Taylan, Osman; Dertli, Enes
An exopolysaccharide (EPS) produced by bee pollen isolate Lactobacillus kunkeei AP-27 was characterised in this study. EPS monomeric composition of strain AP-27 was characterised by High-performance liquid chromatography (HPLC) analysis and glucose was the only sugar in the EPS repeating unit. Structural analysis of glucan AP27 by H-1 and C-13 Nuclear magnetic resonance (NMR) analysis demonstrated that this glucan was a dextran ((1-*6)-linked alpha-D-glucose units as the main body) consisting very low level of (1-* 4)-linked alpha-D-glucose units (similar to 0.5 %). Dextran AP-27 had a degradation temperature of 308 degrees C that revealed its superior thermal strength identified by Thermogravimetric (TGA) and Differential scanning calorimetry (DSC) analysis. The molecular weight of dextran AP-27 was determined to be 25 kDa by Gel Permeation Chromatography (GPC) analysis. Crystallographic properties of dextran AP-27 was determined by X-ray diffraction (XRD) analysis that divulged its amorphous feature. Scanning Electron Microscopy (SEM) analysis was applied for microstructural characterisation of dextran AP-27 which revealed its regular sphere like characteristics. These findings suggest that Lactic Acid Bacteria (LAB) strains from different environments such as bee products can be the source for distinct EPS producer strains.
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, Enes
The 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.
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, Enes
In 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.
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, Osman
Optimisation 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.
MACHINE LEARNING APPLICATION FOR OPTIMIZING ASYMMETRICAL REDUCTION OF ACETOPHENONE EMPLOYING COMPLETE CELL OF LACTOBACILLUS SENMAIZUKE AS AN ENVIRONMENTALLY FRIENDLY APPROACH
(Health & Environment Assoc, 2020) Taylan, Osman; Yilmaz, Mustafa Tahsin; Balubaid, Mohammed; Alamoudi, Rami; El-Obeid, Tahra; Dertli, Enes; Sahin, Engin
Recently, optimization of the bioreduction reactions by optimization methodologies has gained special interest as these reactions are affected by several extrinsic factors that should be optimized for higher yields. An important example for these kinds of reactions is the complete cell implications for the bioreduction of prochiral ketones in which the culture parameters play crucial roles. Such biocatalysts provide environmentally friendly and clean methodology to perform reactions under mild conditions with high conversion rates. In the present work, at the first step the Lactobacillus senmaizuke was isolated from sourdough and the complete cell application of Lactobacillus senmaizuke for the bioreduction of acetophenone was optimized by an Artificial Neural networks (ANNs) to achieve the highest enantiomeric excess (EE, %). The culture parameters, pH, temperature, incubation period and agitation speed were the experimental factors that were optimized to maximize EE (%) by machine learning algorithm of Artificial Intelligence modeling and the best conditions to maximize EE (95.5 %) were calculated to be pH of 5.7, temperature of 35 degrees C, incubation period of 76 h and agitation speed of 240 rpm with very low sum of squared error value (0.611236 %) to bioreduce acetophenone using complete cell of Lactobacillus senmaizuke as a sourdough isolate GRAS microbial species. Accordingly, The ANN was employed to correctly establish the enantiomeric excess values of the specimen with an average absolute error 0.080739 %.
Optimization of asymmetric bioreduction conditions of 1-(thiophen-2-yl)ethanone by Weissella cibaria N9 using a desirability function-embedded face-centered optimization model
(Taylor & Francis Inc, 2023) Bolubaid, Mohammed; Ozdemir, Akin; Dertli, Enes; Alamoudi, Mohammed; Taylan, Osman; Karaboga, Dervis; Yilmaz, Mustafa Tahsin
Prochiral ketones can be effectively bio-reduced to chiral secondary alcohols by whole-cell biocatalysts, which are possible useful precursors to synthesize physiologically active chemicals and natural products. When whole-cell biocatalysts strains are used, bioreduction process can be influenced by various cultural factors, and it is vital to optimize these factors that affect selectivity, conversion rate, and yield. In this study, Weissella cibaria N9 was used as whole-cell biocatalyst for bioreduction of 1-(thiophen-2-yl)ethanone, and cultural design factors were optimized using a desirability function-embedded face-centered optimization model. For this, effects of pH (4.5-5.5-6.5, x(1)), (2) temperature (25-30-35 degrees C, x(2)), (3) incubation period (24-48-72 h, x(3)), and (4) agitation speed (100-150-200 rpm, x(4)) on two response variables; (1) ee (%) and (2) cr (%) were tested. Next, desirability function-embedded face-centered optimization model revealed that a pH of 6.43, a temperature of 26.04 degrees C, an incubation period of 52.41 h, and an agitation speed of 150 rpm were the optimum levels and the estimated ee and cr responses were 99.31% and 98.16%, respectively. Importantly, the actual experimental ee and cr responses were similar to the estimated values indicating the capability of the offered desirability function-embedded face-centered optimization model when using the optimum cultural conditions.
Optimization of asymmetric bioreduction conditions of 1-indanone by Leuconostoc mesenteroides N6 using a face-centered design-based multi-objective optimization model
(Taylor & Francis Inc, 2024) Alamoudi, Mohammed; Ozdemir, Akin; Dertli, Enes; Bolubaid, Mohammed; Alidrisi, Hassan M.; Taylan, Osman; Yilmaz, Mustafa Tahsin
There has been an increasing interest in biocatalysts over the past few decades in order to obtain high efficiency, high yield, and environmentally benign procedures aiming at the manufacture of pharmacologically relevant chemicals. Lactic Acid Bacteria (LAB), a microbial group, can be employed as biocatalysts while performing asymmetric reduction of prochiral ketones. In this study, Leuconostoc mesenteroides N6 was used for the asymmetric bioreduction 1-indanone. And then, a novel and innovative face-centered design-based multi-objective optimization model was used to optimize experimental conditions. Also, the experimental design factors were defined as agitation speed, incubation period, pH, and temperature for optimization to acquire the maximum enantiomeric excess (ee) and conversion rate (cr) values. When using the face-centered design-based multi-objective optimization model, the optimum culture conditions corresponded to 96.34 and 99.42%, ee and cr responses, respectively, were pH = 5.87, incubation temperature = 35 degrees C, incubation period = 50.88 h, and agitation speed = 152.60 rpm. Notably, the validation experiment under the optimum model conditions confirmed the model results. This study demonstrated the importance of the optimization and the efficiency of the face-centered design-based multi-objective model.
Optimization of lactose derivative hetero-oligosaccharides production using whey as the acceptor molecule by an active glucansucrase
(Taylor & Francis Ltd, 2022) Kabli, Mohammad; Ispirli, Humeyra; Balubaid, Mohammed; Taylan, Osman; Yilmaz, Mustafa Tahsin; Dertli, Enes
Glucansucrases are capable of synthesis of distinct oligosaccharides using different acceptor molecules and in this study lactose derivative hetero-oligosaccharides were shown to be produced by an active glucansucrase in its acceptor reaction with sucrose and whey as the donor-acceptor molecules, respectively. Following the monitoring of the reaction products by TLC analysis, the effects of reaction parameters in terms of enzyme concentration, sucrose/whey ratio and reaction temperature on final oligosaccharide yields (OY) were optimized by Response Surface Methodology (RSM). Results indicated that increment of enzyme concentration and reaction temperature decreased the OY in a particular reaction time whereas the OY increased with the increment of sucrose/whey ratio in the acceptor reactions of glucansucrase E81 with whey as the acceptor molecule. A low level of glucansucrase E81 concentration was sufficient to obtain the highest OY in the tested conditions. These findings demonstrated the importance of the optimisation of the reaction parameters for the acceptor reactions of the glucansucrases.
Partial characterization of a levan type exopolysaccharide (EPS) produced by Leuconostoc mesenteroides showing immunostimulatory and antioxidant activities
(Elsevier, 2019) Taylan, Osman; Yilmaz, Mustafa Tahsin; Dertli, Enes
Leuconostoc mesenteroides S81 was isolated from traditional sourdough as an exopolysaccharide (EPS) producer strain. The monosaccharide composition of the EPS from strain S81 was characterized by HPLC analysis and only fructose was found in the repeating unit structure. The NMR spectroscopy analysis revealed that EPS was a levan type EPS as a beta-(2 -> 6)-linked fructan. The MR analysis further confirmed the presence of the furanoid rings in the EPS structure. The levan S81 showed high level of thermal stability determined by DSC and TGA analysis. The lyophilised levan S81 showed a sheet-like compact morphology and its aqueous solution formed spheroidal lumps with a compact structure detected by SEM and AFM analysis, respectively. Importantly the levan S81 showed a high level of immunomodulatory role, induced the anti-inflammatory cytokine IL-4, and exhibited a strong antioxidant capacity with EC50 value 1.7 mg mL(-1) obtained by hydroxyl radical scavenging activity test under in vitro conditions. These findings reveal potential of levan S81 for technological purposes and as a potential natural immunomodulatory and antioxidant. (C) 2019 Elsevier B.V. All rights reserved.
Response surface methodology as optimization strategy for asymmetric bioreduction of acetophenone using whole cell of Lactobacillus senmaizukei
(Taylor & Francis Inc, 2019) Colak, Nida Sezin; Sahin, Engin; Dertli, Enes; Yilmaz, Mustafa Tahsin; Taylan, Osman
Whole cell applications are one of the main methodologies for the bioreduction of prochiral ketones to obtain enantiomerically rich chiral secondary alcohols which are mainly affected by the culture parameters of the whole cell. In this study, whole cell of Lactobacillus senmaizukei as a safe Lactic Acid Bacteria (LAB) was used for the reduction of acetophenone and Response Surface Methodology (RSM) application was used to optimize the culture parameters in terms of temperature, pH, incubation time, and agitation level to obtain the highest enantiomeric excess (ee) and conversion rate. The predicted optimum conditions for the bioreduction with whole cell Lactobacillus senmaizukei were found to be pH of 5.25, temperature of 25 degrees C, incubation time of 72 hr, and agitation level of 100 rpm. Importantly, the efficiency of the reduction of the acetophenone was significantly affected by the linear and quadratic effects of culture parameters. These findings are important to show the role of culture parameters for the bioreduction reactions and also the efficiency of the RSM technique to optimize these parameters.
Structural and bioactive characteristics of a dextran produced by Lactobacillus kunkeei AK1
(Elsevier, 2022) Yilmaz, Mustafa Tahsin; Ispirli, Humeyra; Taylan, Osman; Bilgrami, Anwar L.; Dertli, Enes
In this study, structural and techno-functional characteristics of an exopolysaccharide (EPS) produced by Lactobacillus kunkeei AK1 were determined. High-performance liquid chromatography (HPLC) analysis demonstrated that EPS AK1 was composed of only glucose units. H-1 and C-13 Nuclear magnetic resonance (NMR) analysis revealed that EPS AK1 was a dextran type EPS containing 4.78% (1 -> 4)-linked alpha-D-glucose branches. The molecular weight of EPS AK1 was determined to be 45 kDa by Gel Permeation Chromatography (GPC) analysis. A high level of thermal stability up to 280 degrees C was determined for dextran AK1 detected by Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA). Dextran AK1 appeared as regular spheres with compact morphology and as irregular particles in the solution with no clear cross-linking between the chains of the polysaccharide observed by Scanning electron microscopy (SEM) and Atomic force microscopy (AFM) analysis, respectively. X-ray diffraction analysis (XRD) analysis demonstrated that dextran AK1 had a crystalline structure. A relatively strong antioxidant activity was observed for dextran AK1 determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging and cupric reducing antioxidant capacity (CUPRAC) tests. Finally, only a digestion ratio of 3.1% was observed for dextran AK1 following the in vitro simulated gastric digestion test.
Structural and physicochemical characterisation and antioxidant activity of an ?-D-glucan produced by sourdough isolate Weissella cibaria MED17
(Elsevier, 2020) Aburas, Hani; Ispirli, Humeyra; Taylan, Osman; Yilmaz, Mustafa Tahsin; Dertli, Enes
An exopolysaccharide (EPS) producer slimy-mucoid type colony was isolated from sourdough and identified as Weissella ciboria MED17. The H-1 and C-13 NMR spectra of EPS MED17 demonstrated that this EPS was a dextran type glucan ((1 -> 6)-linked alpha-D-glucose core structure) containing (1 -> 3)-linked alpha-D-glucose branches and proportion of (1 -> 6)-linked alpha-D-glucose units to (1 -> 3)-linked alpha-D-glucose units was 943:5.7%. The MR analysis also confirmed the (1 -> 6)-linked alpha-D-glucose linkage. A high level of thermal stability was observed for glucan MED17 as no degradation up to 300 degrees C was observed by TGA and DSC analysis. The XRD analysis of glucan MED17 showed its semi- crystalline nature and its compact sheet-like morphology was observed by SEM analysis. Finally, antioxidant characteristics of glucan MED17 were determined by ABTS and DPPH radical scavenging activity tests that revealed a moderate antioxidant activity of glucan MED17. These findings show potential techno-functional characteristics of glucan MED17. (C) 2020 Elsevier B.V. All rights reserved.
Synthesis and characterisation of alternan-stabilised silver nanoparticles and determination of their antibacterial and antifungal activities against foodborne pathogens and fungi
(Elsevier, 2020) Yilmaz, Mustafa Tahsin; Ispirli, Humeyra; Taylan, Osman; Dertli, Enes
In this study, alternan isolated from Lactobacillus reuteri E81 was used as the stabilising agent to produce alternan-stabilised silver nanoparticles (AgNPs-Alt) and AgNPs-Alt were characterized and their antibacterial and antifungal activities were tested. The formation and the stability of AgNPs-Alt were determined by UV-vis spectroscopy analysis. SEM and TEM analysis revealed the uniform morphology of AgNPs-Alt with an average size of similar to 50 nm. The crystalline nature of the AgNPs-Alt was confirmed by XRD analysis. The interactions of alternan functional groups with silver was observed by FTIR analysis and thermal characteristics of AgNPs-Alt were determined by DSC analysis. Finally, the antibacterial and the antifungal activities of AgNPs-Alt were tested and AgNPs-Alt revealed inhibitory effects to pathogenic strains at 0.25 mg ml(-1) concentration and this activity was observed to be concentration dependent. For the antifungal activity, a higher level of AgNPs-Alt was required compared to the antibacterial activity.

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