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Levan is a naturally occurring polysaccharide, found in many microorganisms and plants. The polymer is composed of fructose molecules. Food processing industries generate a lot of sugar rich waste consisting of different fruit peels that could be used for levan biosynthesis of levan. The present research presents levan production by Bacillus subtillis via solid state fermentation (SSF) using various sucrose-rich fruit peels. Peels of mango, banana, apple, and sugarcane bagasse were screened and maximum levan yield (1.87 mg/g) was found with mango peels after 24 h at pH 7 and 30 °C. Levan production from mango peel was further optimized for physical parameters using central composite design (CCD) of response surface methodology (RSM). The maximum levan yield (7.586 mg/g) from mango peels was achieved at 120 h incubation, 60% moisture content, 7 pH, and 32 °C. The functional groups of levan were confirmed by FTIR analysis. Sugar content was done by HPLC analysis, which confirmed levan has only fructose sugar. Mango peel could be a potential source for levan production. [ABSTRACT FROM AUTHOR]

Levan is a highly water-soluble biopolymer that has extensive applications in the pharmaceutical, personal care, food, and industrial fields. Lactobacillus fermentum SHN1 was isolated from milk and dairy products as an exopolysaccharide (levan) producer and identified according to morphological, biochemical tests and using the 16S rRNA gene sequencing. The sequence alignment in the gene bank indicated that the isolate has a high percentage of similarity (100%) to the recovered sequence of Lactobacillus fermentum isolate. The produced biopolymer was characterized as levan by FTIR, ¹H-NMR, and 13C-NMR spectroscopy. The effect of various nutritional and physical factors including pH, carbon source, sucrose concentration, nitrogen source, inoculum size, and incubation period, on the synthesis of levan by L. fermentum SHN1 was studied. The findings indicated that the optimal carbon source for the production of levan was 100 g/L sucrose, yielded of 25.95 g/L. Additionally, a combination of peptone + yeast extract at a ratio of 2:0.5 was identified as the most effective nitrogen source for levan production, giving in a yield of 24.21 g/L. L. fermentum SHN1 produces the greatest quantity of levan, 23.89 g/L, under a pH of 6.5 and an inoculum size of 1%, resulting in a yield of 25 g/L. The most favorable period for incubation was 48 hours, resulting in a production yield of 24.87 g/L. [ABSTRACT FROM AUTHOR]

Nanoparticles composed of Levan and Dolutegravir (DTG) have been successfully synthesized using a spray drying procedure specifically designed for milk/food admixture applications. Levan, obtained from the microorganism Bacillus subtilis, was thoroughly characterized using MALDI-TOF and solid-state NMR technique to confirm its properties. In the present study, this isolated Levan was utilized as a carrier for drug delivery applications. The optimized spray-dried nanoparticles exhibited a smooth surface morphology with particle sizes ranging from 195 to 329 nm. In the in-vitro drug release experiments conducted in water media, the spray-dried nanoparticles showed 100 % release, whereas the unprocessed drug exhibited only 50 % release at the end of 24 h. Notably, the drug release in milk was comparable to that in plain media, indicating the compatibility. The improved dissolution rate observed for the nanoparticles could be attributed to the solid-state conversion (confirmed by XRD analysis) of DTG from its crystalline to amorphous state. The stability of the drug was verified using Fourier Transform Infra-Red Spectroscopy and Thermogravimetry-Differential Scanning Calorimetry analysis. To evaluate the in-vitro cellular toxicity, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was conducted, which revealed the CC 50 value of 88.88 ± 5.10 µg/mL for unprocessed DTG and 101.08 ± 37.37 µg/mL for DTG nanoparticles. These results indicated that the toxicity of the nanoparticles was comparable to the unprocessed drug. Furthermore, the anti-HIV activity of the nanoparticles in human cell lines was found to be similar to that of the pure drug, emphasizing the therapeutic efficacy of DTG in combating HIV. [Display omitted] [ABSTRACT FROM AUTHOR]

Eighty-seven bacteria isolates were screened for the presence of the levansucrase encoding gene and those possessing the gene were used in gene expression studies and the production of levan. Based on both screening methods, isolate P19-1 was determined as the producer bacterium with the highest amounts of levan. Whole genome sequencing was done to characterize the isolate and determine its genomic potential. Both its 16 S rRNA and genome were closest to Chromohalobacter salexigens. The levansucrase gene and genes suggesting a versatile carbohydrate and nitrogen metabolism were annotated. A secondary metabolism suggestive of a possible new role in promoting plant growth in hypersaline environments was revealed. The chemical structure analysis of the produced polymer was confirmed by comparison with commercial pure Erwinia herbicola levan. Also, C. salexigens levan showed high biocompatibility. Overall, this is a practical molecular approach that will help researchers to effectively screen microbes with levan production potential. [ABSTRACT FROM AUTHOR]

In this paper, the preparation of three new polysaccharide-type chiral stationary phases (CSPs) based on levan carbamates (3,5-dimethylphenyl, 4-methylphenyl, and 1-naphthyl) is described. The enantioseparation of (±)-trans-β-lactam ureas 1a–h was investigated by high-performance liquid chromatography (HPLC) on six different chiral columns (Chiralpak AD-3, Chiralcel OD-3, Chirallica PST-7, Chirallica PST-8, Chirallica PST-9, and Chirallica PST-10) in the polar organic mode, using pure methanol (MeOH), ethanol (EtOH), and acetonitrile (ACN). Apart from the Chirallica PST-9 column (based on levan tris(1-naphthylcarbamate), the columns exhibited a satisfactory chiral recognition ability for the tested trans-β-lactam ureas 1a–h. [ABSTRACT FROM AUTHOR]

The fabrication of scaffolds that mimic the structure of extracellular matrix molecules using electrospinning has great potential for various tissue engineering applications because it is advantageous for cell ingrowth and tissue formation. In particular, in the case of non-adhesive scaffolds, tissue adhesives (e.g., fibrin, glutaraldehyde) that provide strong adhesion to tissue surfaces or cells are sometimes used to efficiently utilize the desired function. Therefore, scaffolds that combine the advantages of adhesive materials while maintaining cell growth and functionality could further expand tissue engineering applications. In the present study, we developed nanofibers with greatly improved adhesive ability by blended cellulose acetate and levan, a bioadhesive polymer. Nanofibers manufactured through electrospinning exhibited stable mechanical properties through citric acid cross-linking and exhibited excellent adhesive performance with an adhesion strength of up to 3.67 MPa. In future research, we aim to expand the utility of bioadhesive nanofibers by loading nanofiber scaffolds with useful substances for diagnostic and therapeutic purposes. [ABSTRACT FROM AUTHOR]

This study investigated the production of levan biopolymer utilizing cane molasses, an agro-industrial waste, as a substrate. The kinetics of growth, substrate consumption, and levan production by Bacillus megaterium KM3 were examined in bioreactor design employing cane molasses-based media. Experiments were conducted in triplicate to ensure reproducibility, first in a 1L shake flask under optimized conditions, followed by scale-up to a 5L bioreactor, achieving a maximum levan yield as 18.5 g/L. The logistic model for microbial growth and Luedeking–Piret equation for product formation and substrate utilization were found to fit the experimental data, with a maximum specific growth rate constant (µm) as 0.6 h−1. The obtained levan was purified, and monosaccharide analysis by HPLC, confirmed the presence of the fructose monomer. Further structural characterization for the presence of functional group was performed using FTIR. Congo red analysis reveals a triple-helix structure. XRD analysis indicated the levan's non-crystalline amorphous nature, while thermogravimetric analysis demonstrated its high thermal stability. In addition, the in vitro biological activity of levan was evaluated, where it showed strong antioxidant activities to scavenge DPPH radical, hydroxyl radical, and reducing power in dose-dependent manner. The results showcased the promising structural and functional properties of the obtained levan, positioning it as an attractive biopolymer for a wide range of industrial applications. By turning trash into gold, this study provides a model of clean technology's potential to boost productivity while simultaneously lessening its negative effects on the environment. [ABSTRACT FROM AUTHOR]

The valorization of byproducts from the sugarcane industry represents a potential alternative method with a low energy cost for the production of metabolites that are of commercial and industrial interest. The production of exopolysaccharides (EPSs) was carried out using the yeast Suhomyces kilbournensis isolated from agro-industrial sugarcane, and the products and byproducts of this agro-industrial sugarcane were used as carbon sources for their recovery. The effect of pH, temperature, and carbon and nitrogen sources and their concentration in EPS production by submerged fermentation (SmF) was studied in 170 mL glass containers of uniform geometry at 30 °C with an initial pH of 6.5. The resulting EPSs were characterized with Fourier-transform infrared spectroscopy (FT-IR). The results showed that the highest EPS production yields were 4.26 and 44.33 g/L after 6 h of fermentation using sucrose and molasses as carbon sources, respectively. Finally, an FT-IR analysis of the EPSs produced by S. kilbournensis corresponded to levan, corroborating its origin. It is important to mention that this is the first work that reports the production of levan using this yeast. This is relevant because, currently, most studies are focused on the use of recombinant and genetically modified microorganisms; in this scenario, Suhomyces kilbournensis is a native yeast isolated from the sugar production process, giving it a great advantage in the incorporation of carbon sources into their metabolic processes in order to produce levan sucrose, which uses fructose to polymerize levan. [ABSTRACT FROM AUTHOR]

Biopolymers are replacing chemical-based polymers in industrial and biomedical applications owing to their biodegradability and renewability. The present study focuses on the development of cost-effective biosynthesis of exopolysaccharide (EPS) by utilizing agro-industrial waste such as cane molasses as a carbon source by bacterial strain Bacillus megaterium KM3. Investigation into the effect of pretreatments on cane molasses reveals that molasses processed with a combination of heat, acid, tricalcium phosphate, and activated carbon greatly boost EPS production and yield. Plackett–Burman Design and Response Surface Methodology statistical analysis were applied to optimize fermentation medium. The maximum EPS production of 15.75 g/L was obtained at 72 h of fermentation at the optimized medium composition. The EPS was subjected to purification and analysed for monomeric composition by TLC and HPLC analysis, confirms the presence of only fructose monomer. The FT-IR analysis verifies the presence of fructofuranoside units and confirms the EPS is levan type polysaccharide. The use of agro-industrial byproducts as alternative substrates for efficient, low-cost, and scalable EPS synthesis enables new avenues for medium-scale reformulation and sustainable EPS production. EPS offers considerable environmental applications like clay flocculating activity and emulsion activity and, its stability against a variety of hydrocarbon. [ABSTRACT FROM AUTHOR]

Due to its bioactivity and versatile applications, levan has appeared as a promising biomaterial. Levansucrase is responsible for the conversion of sucrose into levan. With the goal of enhancing levan production, the strategy for enhancing the stability of levansucrase is being intensively studied. To make proteins more stable under high temperatures, proline, the most rigid residue, can be introduced into previously flexible regions. Herein, G249, D250, N251, and H252 on the flexible coil close to the calcium binding site of Bacillus licheniformis levansucrase were replaced with proline. Mutations at G249P greatly enhance both the enzyme's thermodynamic and kinetic stability, while those at H252P improve solely the enzyme's kinetic stability. GPC analysis revealed that G249P synthesize more levan, but H252P generate primarily oligosaccharides. Molecular dynamics simulations (MD) and MM/GBSA analysis revealed that G249P mutation increased not only the stability of levansucrase, but also affinity toward fructan. [ABSTRACT FROM AUTHOR]

In this study, levan biopolymer (a fructose-based exopolysaccharide) was produced by Paenibacillus polymyxa HCT33-3, which was immobilized onto the composite of silica-coated magnetite nanoparticles (Fe3O4@SiO2 NPs). For this purpose, firstly, synthesis of magnetite nanoparticles (Fe3O4 NPs) was followed by Fe3O4@SiO2 composite formation to enhance its stability. The characterization studies were investigated with the scanning electron microscopy and energy dispersive X-ray analyzes, transmission electron microscopy, X-ray diffraction analyses. Then, the microorganism Paenibacillus polymyxa HCT33-3, immobilized onto Fe3O4@SiO2 and levan fermentation was carried out in the media including molasses. Effects of molasses percentage in the growth media, initial pH, temperature and fermentation period parameters were tested on levan production capability. The highest levan concentration of 35.8 g/L was obtained at the 54th hour in the medium including 20% molasses (v/v) with the initial pH and temperature values of 7.0 and 37 °C, respectively. The characterization studies clearly confirmed that the produced exopolysaccharide was levan, which showed an antimicrobial effect against all microorganisms used in the study, besides its effectiveness on the biofilm formed by Pseudomonas aeruginosa. This is the first study focusing on high-value levan biopolymer production by the immobilized microorganisms onto Fe3O4@SiO2 nanocomposite in the growth media including molasses as the sole carbon source. This environmentally friendly process, which can potentially enable the repeated use of the cells, seemed to be significantly advantageous in terms of both cost and sustainability. [ABSTRACT FROM AUTHOR]

The demand for sustainable cosmetics leads to the search for natural and biotechnological ingredients. The present study reports the development of a multifunctional lip moisturizer containing levan (LEV) from Bacillus subtilis natto, sophorolipids (SOPs) from Starmerella bombicola and Citrus paradisi (OCP) essential oil, using a simplex-centroid experimental design. The formulations were evaluated physicochemically, pharmacotechnically and by DPPH assay. The optimized formulation was selected through the Response Surface Method, and the evaluation of its efficiency in lip hydration was carried out using the bioimpedance method and sensory analysis. The formulations showed pH compatibility with lips and remained stable after a centrifuge test and thermal stress. Spreadability varied between 415.3 and 1217.1 mm2, moisture retention was above 95% and antioxidant capacity was around 50% for all formulations. The optimized formulation, containing 0.4% LEV and 0.8% SOF, maintained the lip hydration already shown by the participants; 85% of them reported improvement in this aspect. For the first time, LEV and SOP were incorporated in lip moisturizers, which is an environmentally friendly product with marketing potential. Furthermore, the use of the Skin Analyzer Digital equipment, a low-cost and non-invasive technique, to evaluate the effectiveness of lip products is innovative; this methodology may help in the development of future cosmetology studies. [ABSTRACT FROM AUTHOR]

Considering the documented health benefits of bacterial exopolysaccharides (EPSs), specifically of bacterial levan (BL), including its intrinsic antimicrobial activity against certain pathogenic species, the current study concentrated on the development of active pharmaceutical ingredients (APIs) in the form of colloid systems (CoSs) containing silver nanoparticles (AgNPs) employing in-house biosynthesized BL as a reducing and capping agent. The established protocol of fermentation conditions implicating two species of lactic acid bacteria (LAB), i.e., Streptococcus salivarius K12 and Leuconostoc mesenteroides DSM 20343, ensured a yield of up to 25.7 and 13.7 g L−1 of BL within 72 h, respectively. An analytical approach accomplished by Fourier-transform infrared (FT-IR) spectroscopy allowed for the verification of structural features attributed to biosynthesized BL. Furthermore, scanning electron microscopy (SEM) revealed the crystalline morphology of biosynthesized BL with a smooth and glossy surface and highly porous structure. Molecular weight (Mw) estimated by multi-detector size-exclusion chromatography (SEC) indicated that BL biosynthesized using S. salivarius K12 has an impressively high Mw, corresponding to 15.435 × 104 kilodaltons (kDa). In turn, BL isolated from L. mesenteroides DSM 20343 was found to have an Mw of only 26.6 kDa. Polydispersity index estimation (PD = Mw/Mn) of produced BL displayed a monodispersed molecule isolated from S. salivarius K12, corresponding to 1.08, while this was 2.17 for L. mesenteroides DSM 20343 isolate. The presence of fructose as the main backbone and, to a lesser extent, glucose and galactose as side chain molecules in EPS hydrolysates was supported by HPLC-RID detection. In producing CoS-BL@AgNPs within green biosynthesis, the presence of nanostructured objects with a size distribution from 12.67 ± 5.56 nm to 46.97 ± 20.23 was confirmed by SEM and energy-dispersive X-ray spectroscopy (EDX). The prominent inhibitory potency of elaborated CoS-BL@AgNPs against both reference test cultures, i.e., Pseudomonas aeruginosa, Escherichia coli, Enterobacter aerogenes, and Staphylococcus aureus and those of clinical origin with multi-drug resistance (MDR), was confirmed by disc and well diffusion tests and supported by the values of the minimum inhibitory and bactericidal concentrations. CoS-BL@AgNPs can be treated as APIs suitable for designing new antimicrobial agents and modifying therapies in controlling MDR pathogens. [ABSTRACT FROM AUTHOR]

Hydrogels in active wound care products are 3D polymeric scaffolds that provide the desired moisture balance in the wound area with their high water retention capacity. Thanks to their biocompatible properties, flexible and porous structures, and high hydrophilic properties, they have frequently been preferred in the repair and regeneration of cells and tissues and the controlled release of bioactive substances to the target area. In this study, hydrogel structures were developed for the first time with levan produced by Halomonas elongata 153B halophilic bacteria. Extracts from Plantago lanceolata L., commonly known as a wound herb, which has medicinal importance for cell regeneration, ensuring tissue integrity in a short time and reducing infections in the wound area, were obtained and extract-loaded liposome structures were formed for controlled release into the wound area. The wound healing efficacy of the composite material developed by loading herbal liposomes into levan-based hydrogel structures was evaluated in an in vitro wound model. Thus, a natural, biocompatible, biodegradable, and functional wound care product containing herbal liposomes suitable for both clinical applications and point-of-care use has been developed. The developed bioactive hydrogels are a promising therapeutic approach for the healing of acute wounds. [ABSTRACT FROM AUTHOR]

• Interpenetrating network (IPN) based levan-polyacrylamide hydrogels were applied in the field of conservation of cultural heritage for the first time. • Hydrogels produced with microbially, and enzymatically produced levan polymers performed equally well suggesting negligible effect of the levan synthesis route. • Swelling of the hydrogels was increased almost 3-fold with the addition of levan into the polymer network. • Levan-Polyacrylamide hydrogels demonstrate higher swelling capacity as the medium gets more alkaline. • Solvent loaded hydrogels were applied onto two bindings of 19th century printed book with the aim of removing adhesive tapes that would cause further damage in the future. In this study, an IPN based enzymatic levan-polyacrylamide hydrogel (EL-PA) was developed and characterized for its structural, morphological, rheological properties and swelling kinetics to underline hydrogel properties and its potential use in paper conservation. The addition of levan also led to changes in the viscoelastic behavior of the hydrogels, with the complex viscosity of EL-PA samples showing pronounced dependence on shear rate. The swelling and the overall surface area of the hydrogels were increased with the addition of levan into the polymer network. Source associated structural differences were found to be negligible such that both microbially produced linear and enzymatically produced branched forms of levan performed equally well. Solvent loaded hydrogels were then applied on an artifact, a 19th century book of Namık Kemal, and investigated using FTIR, SEM, XRD and colorimetric analysis. Old adhesive layers were successfully removed, and hydrogels showed good compatibility and ease of application. This study has shown that levan has improved hydrogel properties and levan based systems bear high potential in conservation science. [ABSTRACT FROM AUTHOR]

In this paper, the preparation of three new polysaccharide-type chiral stationary phases (CSPs) based on levan carbamates (3,5-dimethylphenyl, 4-methylphenyl, and 1-naphthyl) is described. The enantioseparation of (±)-trans-β-lactam ureas 1a–h was investigated by high-performance liquid chromatography (HPLC) on six different chiral columns (Chiralpak AD-3, Chiralcel OD-3, Chirallica PST-7, Chirallica PST-8, Chirallica PST-9, and Chirallica PST-10) in the polar organic mode, using pure methanol (MeOH), ethanol (EtOH), and acetonitrile (ACN). Apart from the Chirallica PST-9 column (based on levan tris(1-naphthylcarbamate), the columns exhibited a satisfactory chiral recognition ability for the tested trans-β-lactam ureas 1a–h.

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The trisaccharide 1-kestose, a major constituent of fructooligosaccharide, has strong prebiotic effects. We used high-performance liquid chromatography and 1H nuclear magnetic resonance spectroscopy to show that BiBftA, a β-fructosyltransferase belonging to glycoside hydrolase family 68, from Beijerinckia indica subsp. indica catalyzes transfructosylation of sucrose to produce mostly 1-kestose and levan polysaccharides. We substituted His395 and Phe473 in BiBftA with Arg and Tyr, respectively, and analyzed the reactions of the mutant enzymes with 180 g/L sucrose. The ratio of the molar concentrations of glucose and 1-kestose in the reaction mixture with wild-type BiBftA was 100:8.1, whereas that in the reaction mixture with the variant H395R/F473Y was 100:45.5, indicating that H395R/F473Y predominantly accumulated 1-kestose from sucrose. The X-ray crystal structure of H395R/F473Y suggests that its catalytic pocket is unfavorable for binding of sucrose while favorable for transfructosylation. BiBftA catalyzed transfructosylation of sucrose to produce 1-kestose, and H395R/F473Y variant predominantly accumulated 1-kestose. [ABSTRACT FROM AUTHOR]

Copyright of China Condiment is the property of China Condiment and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, we report high molecular weight (HMW) levan production by whole cells of Microbacterium paraoxydans , previously reported to be a good producer of fructooligosaccharides. Structural analysis of the extracellularly produced fructan indicated the glycosidic bonds between the adjacent fructose to be of β-(2, 6) linkage with over 90% of the fructan to have molecular weight around 2 × 108 Da and 10% with a molecular weight of ∼20 kDa. Immobilization of the cells in Ca-alginate led to the production of 44.6 g/L levan with a yield of 0.29 g/g sucrose consumed. Factors affecting the conversion rate were identified by One-Factor-At-a-Time (OFAT) analysis and the combination of these (initial sucrose concentration of 400 g/L, 100 mM buffer pH 7, the temperature of 37 °C and 20 mM CaCl 2) led to the production of ∼129 g/L of levan with a yield of ∼0.41 g/g sucrose consumed and volumetric productivity of 1.8 g/L/h. • High molecular weight levan synthesis by Microbacterium paraoxydans. • Sucrose utilization and levan production enhanced in Ca-alginate entrapped cells. • One-Factor-At-A-Time approach for production of 129 g/L levan by immobilized cells. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are extensively investigated for their potential physical, chemical, and biological properties. Silver nanoparticles (AgNPs) have several applications in diagnosis, therapy (wound healing, cancer), electronic devices, water treatment, etc. The present study used the cost-effective and ecologically approachable technique to synthesize levan-capped silver nanoparticles of about 22 nm. These silver nanoparticles were subsequently introduced into a gel to create a silver release system with bacteria inhibition activity. The study also aimed to evaluate synthesized Levan-based silver nanoparticles loaded gel for its wound healing property in the excision rat model. Compared to commercial products, levan-based AgNPs were used for in-vitro antimicrobial activities on E. Coli and Staphylococcus aureus and in-vivo wound healing properties.The wound healing property was assessed by area and time of wound closure in rats. In the excision wound model, Levan-based AgNPs exhibited a reduction in wound area that was more as compared to standard and control. In this study, the nanoparticles of silver were spherical and homogeneous in size, which showed bactericidal effects for E. coli and B. subtilis. Levan acts as a coating and reducing agent for silver nanoparticles and acts as an anti-inflammatory agent in the healing process. Carbopol was used for topical formulations such as hydrogel due to high viscosity at low concentration and low toxicity profile. This polymer is anionic that needs to be neutralized with triethanolamine to become jellified, and it has good bio-adhesive properties required for gel formulation. The present challenge of silver nanoparticles (AgNPs) is to maximize their benefits and minimize their toxic effects on humans and the environment. For future perspective, its synthesis, release into the atmosphere, and scaling up production must be considered.

Polysaccharides are essential components with diverse functions in living organisms and find widespread applications in various industries. They serve as food additives, stabilizers, thickeners, and fat substitutes in the food industry, while also contributing to dietary fiber for improved digestion and gut health. Plant-based polysaccharides are utilized in paper, textiles, wound dressings, biodegradable packaging, and tissue regeneration. Polysaccharides play a crucial role in medicine, pharmacy, and cosmetology, as well as in the production of biofuels and biomaterials. Among microbial biopolymers, microbial levan, a fructose polysaccharide, holds significant promise due to its high productivity and chemical diversity. Levan exhibits a wide range of properties, including film-forming ability, biodegradability, non-toxicity, self-aggregation, encapsulation, controlled release capacity, water retention, immunomodulatory and prebiotic activity, antimicrobial and anticancer activity, as well as high biocompatibility. These exceptional properties position levan as an attractive candidate for nature-based materials in food production, modern cosmetology, medicine, and pharmacy. Advancing the understanding of microbial polymers and reducing production costs is crucial to the future development of these fields. By further exploring the potential of microbial biopolymers, particularly levan, we can unlock new opportunities for sustainable materials and innovative applications that benefit various industries and contribute to advancements in healthcare, environmental conservation, and biotechnology. [ABSTRACT FROM AUTHOR]

One thermotolerant Bacillus strain SFLV-ZM107 which could produce large amounts of extracellular polysaccharides (EPS) at 50°C was identified as Bacillus licheniformis by 16S rDNA sequencing and physiological and biochemical experiments. The EPS was identified as levan fructan by monosaccharides determination, NMR, and FTIR. Strain SFLV-ZM107 can be grown in the range of 35–55°C and it is efficient to produce levan from 400 to 500 g l−1 of sucrose. The production of levan can reach 158 g l−1 in a 5 L tank fermentation with an initial sucrose concentration of 450 g l−1 at 50°C for 12 hours with a maximum productivity of 13.17 g l−1 h−1. To the best of our knowledge, the strains obtained in this study are the most productive and efficient, which has great prospects for industrial application. [ABSTRACT FROM AUTHOR]

Bacterial exopolysaccharides (EPS) are essential natural biopolymers used in different areas including biomedicine, food, cosmetic, petroleum, and pharmaceuticals and also in environmental remediation. The interest in them is primarily due to their unique structure and properties such as biocompatibility, biodegradability, higher purity, hydrophilic nature, anti-inflammatory, antioxidant, anti-cancer, antibacterial, and immune-modulating and prebiotic activities. The present review summarizes the current research progress on bacterial EPSs including their properties, biological functions, and promising applications in the various fields of science, industry, medicine, and technology, as well as characteristics and the isolation sources of EPSs-producing bacterial strains. This review provides an overview of the latest advances in the study of such important industrial exopolysaccharides as xanthan, bacterial cellulose, and levan. Finally, current study limitations and future directions are discussed. [ABSTRACT FROM AUTHOR]

Levan is a homopolysaccharide of fructose units that repeat as its structural core. As an exopolysaccharide (EPS), it is produced by a great variety of microorganisms and a small number of plant species. The principal substrate used for levan production in industries, i.e., sucrose, is expensive and, hence, the manufacturing process requires an inexpensive substrate. As a result, the current research was designed to evaluate the potential of sucrose-rich fruit peels, i.e., mango peels, banana peels, apple peels, and sugarcane bagasse, to produce levan using Bacillus subtilis via submerged fermentation. After screening, the highest levan-producing substrate, mango peel, was used to optimize several process parameters (temperature, incubation time, pH, inoculum volume, and agitation speed) employing the central composite design (CCD) of response surface methodology (RSM), and their impact on levan production was assessed. After incubation for 64 h at 35 °C and pH 7.5, the addition of 2 mL of inoculum, and agitation at 180 rpm, the highest production of levan was 0.717 g/L of mango peel hydrolysate (obtained from 50 g of mango peels/liter of distilled water). The F-value of 50.53 and p-value 0.001 were calculated using the RSM statistical tool to verify that the planned model was highly significant. The selected model's accuracy was proven by a high value (98.92%) of the coefficient of determination (R2). The results obtained from ANOVA made it clear that the influence of agitation speed alone on levan biosynthesis was statistically significant (p-value = 0.0001). The functional groups of levan produced were identified using FTIR (Fourier-transform ionization radiation). The sugars present in the levan were measured using HPLC and the levan was found to contain only fructose. The average molecular weight of the levan was 7.6 × 106 KDa. The findings revealed that levan can be efficiently produced by submerged fermentation using inexpensive substrate, i.e., fruit peels. Furthermore, these optimized cultural conditions can be applied on a commercial scale for industrial production and commercialization of levan. [ABSTRACT FROM AUTHOR]

The valorization of byproducts from the sugarcane industry represents a potential alternative method with a low energy cost for the production of metabolites that are of commercial and industrial interest. The production of exopolysaccharides (EPSs) was carried out using the yeast Suhomyces kilbournensis isolated from agro-industrial sugarcane, and the products and byproducts of this agro-industrial sugarcane were used as carbon sources for their recovery. The effect of pH, temperature, and carbon and nitrogen sources and their concentration in EPS production by submerged fermentation (SmF) was studied in 170 mL glass containers of uniform geometry at 30 °C with an initial pH of 6.5. The resulting EPSs were characterized with Fourier-transform infrared spectroscopy (FT-IR). The results showed that the highest EPS production yields were 4.26 and 44.33 g/L after 6 h of fermentation using sucrose and molasses as carbon sources, respectively. Finally, an FT-IR analysis of the EPSs produced by S. kilbournensis corresponded to levan, corroborating its origin. It is important to mention that this is the first work that reports the production of levan using this yeast. This is relevant because, currently, most studies are focused on the use of recombinant and genetically modified microorganisms; in this scenario, Suhomyces kilbournensis is a native yeast isolated from the sugar production process, giving it a great advantage in the incorporation of carbon sources into their metabolic processes in order to produce levan sucrose, which uses fructose to polymerize levan.

An alternate medium consisting of sugarcane juice (SJ) (Saccharum spp.) and chicken feather peptone (CFP) was employed for microbial synthesis of levan. SJ has considerable amounts of vital minerals, vitamins, and amino acids in addition to its major constituent, sucrose. Meanwhile, CFP is also a rich source of essential nutrients such as amino acids, micro and macro elements. Amino acids present in SJ and CFP, such as glutamic acid, arginine, aspartic acid, asparagine and elements such as Ca, Mg favoured the cell growth and levan production. In this present work, levan was produced using Bacillus subtilis MTCC 441 in five different media, namely, sucrose along with defined nutrients (M1), Sugarcane Juice without nutrients (M2), SJ with defined nutrients (M3), SJ along with chicken feather peptone (M4) and sucrose without nutrient (M5). Alternative nutrient medium using SJ and CFP (M4) showed a promising levan yield of 0.32 ± 0.01 g of levan/g of sucrose consumed, which is 64% of the theoretical levan yield possible. Levan produced was characterized using Nuclear Magnetic Resonance (NMR) and Gel Permeation Chromatography (GPC). There is a change in low molecular weight fractions of levan obtained from SJ and CFP medium compared to the defined medium. Produced levan from the composite medium exhibited strong antioxidant activity and was biocompatible when tested against endothelial cells. The substrate cost was 20% lower than the cost of defined medium. Thus, a composite medium made of SJ and CFP can serve as an alternate low-cost medium for microbial fermentation.

A strain, 3EQS1, was isolated from a salt sample taken from Lake Qarun (Fayoum Province, Egypt). On the basis of physiological, biochemical, and phylogenetic analyses, the strain was classified as Chromohalobacter salexigens. By 72 h of growth at 25 °C, strain 3EQS1 produced large amounts (15.1 g L−1) of exopolysaccharide (EPS) in a liquid mineral medium (initial pH 8.0) containing 10% sucrose and 10% NaCl. The EPS was precipitated from the cell-free culture medium with chilled ethanol and was purified by gel-permeation and anion-exchange chromatography. The molecular mass of the EPS was 0.9 × 106 Da. Chemical analyses, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy showed that the EPS was a linear β-d-(2 → 6)-linked fructan (levan). In aqueous solution, the EPS tended to form supramolecular aggregates with a critical aggregation concentration of 240 µg mL−1. The EPS had high emulsifying activity (E24, %) against kerosene (31.2 ± 0.4%), sunflower oil (76.9 ± 1.3%), and crude oil (98.9 ± 0.8%), and it also had surfactant properties. A 0.1% (w/v) aqueous EPS solution reduced the surface tension of water by 11.9%. The levan of C. salexigens 3EQS1 may be useful in various biotechnological processes. [ABSTRACT FROM AUTHOR]

Halophilic organisms are a novel attractive option as cell factories for the production of industrially valuable bioproducts. Halomonas elongata is the cell factory of choice for ectoine production, but its levan production has not been well researched. Based on this scientific motivation, in this study, we evaluated the chemical and biological properties of levan produced by the halophilic extremophile Halomonas elongata 153B (HeL). First, the central composite design was used to determine the optimal process variables for maximum levan biosynthesis. Then, the levan produced from HeL was purified, quantified, and chemically characterized with FTIR, 1H-NMR, and GPC analyses. This was followed by antioxidant, anti-inflammatory, antibiofilm, and antimicrobial activity tests to assess its biological activities as well as a cytotoxcity assay. Maximum levan yields of 5.13 ± 0.38 g/L were achieved after dialysis at the optimum levels of process variables. The 1H-NMR spectrum of HeL revealed characteristic signals. It showed a strong antioxidant activity of 67.88% and the best radical scavenger. At a concentration of 400 µg/mL, HeL showed the most anti-inflammatory efficacy. Also, at all indicated concentrations (250, 500, 750, and 1000 μg/mL) HeL, acted against biofilms formed by Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 11778, Candida albicans ATCC 10231. Furthermore, HeL displayed antimicrobial activities against all strains tested. Finally, HeL showed high Cell viability in all dosages and no cytotoxicity was observed. In light of these results, HeL may have high potential in the medical, pharmaceutical and dermo-cosmetics industries. [ABSTRACT FROM AUTHOR]

Paenibacillus antarcticus IPAC21, an endospore-forming and bioemulsifierproducing strain, was isolated from King George Island, Antarctica. As psychrotolerant/psychrophilic bacteria can be considered promising sources for novel products such as bioactive compounds and other industrially relevant substances/compounds, the IPAC21 genome was sequenced using Illumina Hi-seq, and a search for genes related to the production of bioemulsifiers and other metabolic pathways was performed. The IPAC21 strain has a genome of 5,505,124 bp and a G + C content of 40.5%. Genes related to the biosynthesis of exopolysaccharides, such as the gene that encodes the extracellular enzyme levansucrase responsible for the synthesis of levan, the 2,3-butanediol pathway, PTS sugar transporters, cold-shock proteins, and chaperones were found in its genome. IPAC21 cell-free supernatants obtained after cell growth in trypticase soy broth at different temperatures were evaluated for bioemulsifier production by the emulsification index (EI) using hexadecane, kerosene and diesel. EI values higher than 50% were obtained using the three oil derivatives when IPAC21 was grown at 28°C. The bioemulsifier produced by P. antarcticus IPAC21 was stable at different NaCl concentrations, low temperatures and pH values, suggesting its potential use in lower and moderate temperature processes in the petroleum industry. [ABSTRACT FROM AUTHOR]

The biological production of levan by levansucrase (LS, EC 2.4.1.10) has aroused great interest in the past few years. Previously, we identified a thermostable levansucrase from Celerinatantimonas diazotrophica (Cedi-LS). A novel thermostable LS from Pseudomonas orientalis (Psor-LS) was successfully screened using the Cedi-LS template. The Psor-LS showed maximum activity at 65 °C, much higher than the other LSs. However, these two thermostable LSs showed significantly different product specificity. When the temperature was decreased from 65 to 35 °C, Cedi-LS tended to produce high-molecular-weight (HMW) levan. By contrast, Psor-LS prefers to generate fructooligosaccharides (FOSs, DP ≤ 16) rather than HMW levan under the same conditions. Notably, at 65 °C, Psor-LS would produce HMW levan with an average Mw of 1.4 × 106 Da, indicating that a high temperature might favor the accumulation of HMW levan. In summary, this study allows a thermostable LS suitable for HMW levan and levan-type FOSs production simultaneously. [ABSTRACT FROM AUTHOR]

Levan is a biopolymer composed of fructose chains covalently linked by β−2,6 glycosidic linkages. This polymer self−assembles into a nanoparticle of uniform size, making it useful for a wide range of applications. Also, levan exhibits various biological activities such as antioxidants, anti-inflammatory, and anti-tumor, that make this polymer very attractive for biomedical application. In this study, levan synthesized from Erwinia tasmaniensis was chemically modified by glycidyl trimethylammonium chloride (GTMAC) to produce cationized nanolevan (QA-levan). The structure of the obtained GTMAC−modified levan was determined by FT-IR, 1H-NMR and elemental (CHN) analyzer. The size of the nanoparticle was calculated using the dynamic light scattering method (DLS). The formation of DNA/QA-levan polyplex was then investigated by gel electrophoresis. The modified levan was able to increase the solubility of quercetin and curcumin by 11-folds and 205-folds, respectively, compared to free compounds. Cytotoxicity of levan and QA−levan was also investigated in HEK293 cells. This finding suggests that GTMAC−modified levan should have a potential application for drug and nucleic acid delivery. [ABSTRACT FROM AUTHOR]

Human epidermal growth factor (hEGF) has been a subject of extensive research as its wide range of physiological functions has many potential applications. However, due to the low stability of hEGF, its physiological effect is easily lost under conditions of use. To compensate for this, we developed a stable delivery system using levan-based nanoparticles. The entrapment yield of various tested proteins was significantly improved by employing carboxymethyl levan (CML) instead of levan; the entrapment yield of the CML-hEGF nanoparticles was 84.1 %. The size and zeta potential of the nanoparticles were identified as 199.9 ± 3.87 nm and −19.1 mV, respectively, using scanning electron microscopy (SEM) and particle size analysis. Dual biological functions of the nanoparticles (skin regeneration and moisturizing) were identified through collagen synthesis activity and aquaporin 3 expression level analysis. Stability of the prepared nanoparticles was also investigated via cell proliferation activity comparison under mimicked physiological conditions. The CML-hEGF nanoparticles maintained cell proliferation activity over 100 % for 6 weeks, while free hEGF was almost inactivated within 2 weeks. Taken together, our results indicate that the CML-based hEGF nanoparticles can be used in pharma- and cosmeceutical applications, guaranteeing a high entrapment capability, functionality, and stability. [ABSTRACT FROM AUTHOR]

Although electrospun nanofibers have great potential for various tissue engineering applications, owing to their large surface area and extracellular matrix-mimicking properties, their lack of appropriate mechanical strength and biological cues for cell adhesion and proliferation limits their widespread use in tissue engineering. Nanofiber composite possessing two or more desired properties and functions has garnered considerable attention regarding its utility in diverse biomedical applications. In the present study, we aimed to develop a mechanically reinforced electrospun composite nanofiber by blending cellulose acetate and levan. Crosslinking the composite nanofiber with citric acid could significantly enhance its mechanical properties and thermal stability. In fact, the composite nanofibers had an adhesive strength of up to 1.27 MPa, which is similar to that of commercial tissue adhesive fibrin glue. The bioadhesive trait of composite nanofiber and the unique properties of levan not only enabled remarkable biocompatibility but also improved the levels of cell attachment and proliferation. Overall, the developed electrospun composite nanofibers can be used as promising cell scaffolds in tissue regenerative cell therapy. [ABSTRACT FROM AUTHOR]

Enterotoxigenic Escherichia coli (ETEC)-mediated diarrhea can be mitigated by inhibiting bacterial adhesion to intestinal surface. Some lactic acid bacteria (LAB) produce exopolysaccharides (EPS) that can inhibit ETEC adhesion. In this study, we fermented soy flour-based dough (SoyD) with EPS-producing LAB strains Pediococcus pentosaceus TL (Pp TL), Leuconostoc citreum TR (Lc TR), Leuconostoc mesenteroides WA (Lm WA) and L. mesenteroides WN (Lm WN) to improve anti-adhesive activity of the dough against ETEC. The strains Lc TR, Lm WA and Lm WN produced EPS in SoyD fermentation with similar polysaccharide yields and compositions as when grown in liquid medium, whereas Pp TL was unable to produce EPS in SoyD. Lc TR produced high molecular weight (Mw) dextran (∼900 kDa) while Lm WA and Lm WN produced dextran and levan with diverse Mw (∼20–1000 kDa). SoyD fermentation by EPS-producing LAB increased the capability of the SoyD extracts to adhere to ETEC cells and block ETEC adhesion to porcine mucin. After Mw-based fractionation, all extract-fractions (>3 kDA) of Lm WA- and Lm WN-fermented SoyD retained their blocking activity indicating that various Mw populations of the EPS contributes to bioactivity against ETEC. This study shows the potential of EPS-producing LAB strains as fermenting microorganisms in the development of a functional food product with anti-diarrheal properties. [Display omitted] [ABSTRACT FROM AUTHOR]