Fermentation parameters and conditions affecting levan production and its potential applications in cosmetics

Bacterial extracellular biopolymers: Eco-diversification, biosynthesis, technological development and commercial applications

Synthetic polymers have been widely thriving as mega industries at a commercial scale in various commercial sectors over the last few decades. The extensive use of synthetic polymers has caused several negative repercussions on the health of humans and the environment. Recently, biopolymers have gained more attention among scientists of different disciplines by their potential therapeutic and commercial applications. Biopolymers are chain-like repeating units of molecules isolated from green sources. They are self-degradable, biocompatible, and non-toxic in nature. Recently, eco-friendly biopolymers such as extracellular polymeric substances (EPSs) have received much attention for their wide applications in the fields of emulsification, flocculation, preservatives, wastewater treatment, nanomaterial functionalization, drug delivery, cosmetics, glycomics, medicinal chemistry, and purification technology. The dynamicity of applications has raised the industrial and consumer demands to cater to the needs of mankind. This review deals with current insights and highlights on database surveys, potential sources, classification, extremophilic EPSs, bioprospecting, patents, microenvironment stability, biosynthesis, and genetic advances for production of high valued ecofriendly polymers. The importance of high valued EPSs in commercial and industrial applications in the global market economy is also summarized. This review concludes with future perspectives and commercial applications for the well-being of humanity.

Exploring the role of levan in plant immunity to pathogens: A review

This review article delves into the intricate relationship between levan, a versatile polysaccharide, and its role in enhancing plant resistance against pathogens. By exploring the potential applications of levan in agriculture and biotechnology, such as crop protection, stress tolerance enhancement, and biotechnological innovations, significant advancements in sustainable agriculture are uncovered. Despite challenges in optimizing application methods and addressing regulatory hurdles, understanding the mechanisms of levan-mediated plant immunity offers promising avenues for future research. This review underscores the implications of utilizing levan to develop eco-friendly solutions, reduce reliance on chemical pesticides, and promote sustainable agricultural practices. Ultimately, by unraveling the pivotal role of levan in plant-pathogen interactions, this review sets the stage for transformative innovations in agriculture and highlights the path towards a more resilient and sustainable agricultural future.

Expanding the horizons of levan: from microbial biosynthesis to applications and advanced detection methods

Levan, a β-(2,6)-linked fructose polymer, exhibits diverse properties that impart versatility, rendering it a highly sought-after biopolymer with various industrial applications. Levan can be produced by various microorganisms using sucrose, food industry byproducts and agricultural wastes. Microbial levan represents the most potent cost-effective process for commercial-scale levan production. This study reviews the optimization of levan production by understanding its biosynthesis, physicochemical properties and the fermentation process. In addition, genetic and protein engineering for its increased production and emerging methods for its detection are introduced and discussed. All of these comprehensive studies could serve as powerful tools to optimize levan production and broaden its applications across various industries.

Sustainable production of heavy metal-binding levan by a subarctic permafrost thaw lake Pseudomonas strain 2ASCA

Pseudomonas strain 2ASCA isolated in subarctic Québec, Canada, produced a cell membrane bound levan-type exopolymer (yield 1.17 g/L), after incubation in growth media containing 6 % sucrose (w/v) at temperature of 15 °C for 96 h. The objective of this study was to optimize levan production by varying the growth parameters. Moreover, the polymer's chemical characterization has been studied with the aim of increasing knowledge and leading to future applications in many fields, including heavy metal remediation. Higher levan yields (7.37 g/L) were reached by setting up microbial fermentation conditions based on the re-use of the molasses obtained from sugar beet processing. Spectroscopy analyses confirmed the levan-type nature of the exopolymer released by strain 2ASCA, consisting of a β-(2,6)-linked fructose repeating unit. Gel permeation chromatography revealed that the polymer has a molecular weight of 13 MDa. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) showed that the levan sequestered with a strong affinity Cr(III), which has never been previously reported, highlighting an interesting biosorption potential. In addition, SEM analysis revealed the formation of nanoparticles in acidified water solution.

Levan Production by Suhomyces kilbournensis Using Sugarcane Molasses as a Carbon Source in Submerged Fermentation

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.

Evolving Advances in the Cosmetic use of Probiotics and Postbiotics: Health, Regulatory and Marketing Aspects

Ongoing development in cosmetics is increasingly making use of probiotics, which are defined as "live microorganisms with health-enhancing properties mediated through ingestion or topical application to the host". The observation that several bacterial strains augment normal processes of healthy tissue maintenance, particularly for the skin, has opened up new avenues for the use of bacterial strains in cosmetics. A principal feature of such "cosmeceuticals" is an application of increasing insight into the biochemical nature of the skin's normal microbial flora, also called its microbiome. The opportunity of manipulating the skin microbiome to address various skin disorders has revealed novel routes for treatment. The skin microbiome manipulation approaches to address various skin disorders include skin microbiome transplantation, skin bacteriotherapy, and prebiotic stimulation. Research in this field has revealed that medical outcome-targeted manipulation of skin microbiome bacterial strain makeup may significantly increase skin health and appearance. Commercial availability of probiotic skincare products is rapidly expanding worldwide due to satisfactory laboratory results and public perception of probiotics as being intrinsically more wholesome than other bioactive substances, such as synthetics. Major outcomes of probiotic use include a significant reduction in skin wrinkling, acne and other conditions adversely affecting skin appearance and healthy function. Moreover, probiotics may additionally promote normal skin hydration, resulting in a vibrant and lustrous appearance. Nevertheless, significant technical challenges remain for the full optimization of probiotics in cosmetic products. This article summarizes the evolving nature of this field and explores current probiotic research initiatives, along with regulatory aspects and significant challenges in the manufacturing of cosmetics in the context of market expansion for these products.

Characterization of levans produced by levansucrases from Bacillus amyloliquefaciens and Gluconobacter oxydans: Structural, techno-functional, and anti-inflammatory properties

Levans of different structures and molecular weights (MW) can display various techno-functional and health-promoting properties. In the present study, selected levans were produced by the transfructosylation of sucrose catalyzed by levansucrases from Bacillus amyloliquefaciens and Gluconobacter oxydans, and their structural, techno-functional and anti-inflammatory properties were investigated. NMR and methylation/GC analysis confirmed the structure of β-(2, 6) levans. The structural characterization led to the classification of levans as high MW (HMW, ≥100 kDa), low MW (LMW, ≤20 kDa) and mix L/HMW ones. Levan with higher MW had more linear fructosyl units with fewer reducing ends and branching residues. LMW levan showed the highest foaming capacity and stability while HMW levan had the highest emulsion stability. HMW and mix L/HMW levans showed comparable water and oil-holding capacities, which were higher than LMW. HMW and mix L/HMW levans were found to have gelling properties at low concentrations. The rheological behaviour of HMW levan-based gel was a more viscous-like gel, while that of mix L/HMW levan-based one showed more elastic solid like-gel. The temperature also influenced the rheology of levan, showing that the mix L/HMW levan gel network was the most thermal stable as its viscoelasticity remained constant at the highest temperature (75 °C). Studies on the biological activity of levans of HMW and LMW revealed in-vitro anti-inflammatory properties as they significantly reduced the production of LPS-triggered pro-inflammatory cytokines in differentiated Caco-2 cells.

Fabrication and characterization of new levan@CBD biocomposite sponges as potential materials in natural, non-toxic wound dressing applications

Wound healing is a complex process; therefore, new dressings are frequently required to facilitate it. In this study, porous bacterial levan-based sponges containing cannabis oil (Lev@CBDs) were prepared and fully characterized. The sponges exhibited a suitable swelling ratio, proper water vapor transmission rate, sufficient thermal stability, desired mechanical properties, and good antioxidant and anti-inflammatory properties. The obtained Lev@CBD materials were evaluated in terms of their interaction with proteins, human serum albumin and fibrinogen, of which fibrinogen revealed the highest binding effect. Moreover, the obtained biomaterials exhibited antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, as well as being non-hemolytic material as indicated by hemolysis tests. Furthermore, the sponges were non-toxic and compatible with L929 mouse fibroblasts and HDF cells. Most significantly, the levan sponge with the highest content of cannabis oil, in comparison to others, retained its non-hemolytic, anti-inflammatory, and antimicrobial properties after prolonged storage in a climate chamber at a constant temperature and relative humidity. The designed sponges have conclusively proven their beneficial physicochemical properties and, at the preliminary stage, biocompatibility as well, and therefore can be considered a promising material for wound dressings in future in vivo applications.

Characterization, production optimization, and fructanogenic traits of levan in a new Microbacterium isolate

Levan is a high-valued β-(2,6)-linked fructan with promising physicochemical and physiological properties and has diverse potential applications in the food, nutraceutical, pharmaceutical and cosmetic industry, but its commercial availability is still restricted to the relatively high costs of production. In this study, a strain identified as Microbacterium sp. XL1 was isolated from soil and highly produced exopolysaccharide (EPS). HPLC, FTIR and NMR spectroscopy revealed XL1-EPS is a levan-type fructan connected by β-(2, 6) linkages. SEM, DLS and TGA-DSC analysis showed that XL1-EPS processed high morphological versatility, narrow size distribution in its solutions and excellent thermal stability. The levan yield reached 83.67 ± 4.06 g/L with corresponding productivity of 3.49 ± 0.17 g/L/h and a conversion yield of 39.8 ± 1.9 % using sucrose (210 g/L) as substrates under the optimal cultivation conditions concluded by the response surface methodology (RSM). More strikingly, the XL1 strain also has multi-type fructanases to generate levanbiose, kestose, DFA IV and other L-FOSs. These results suggest Microbacterium sp. XL1 is a promising strain to produce levan and can provide various levan/inulin-degrading enzymes to create a great diversity of FOSs.

Recent Developments and Applications of Microbial Levan, A Versatile Polysaccharide-Based Biopolymer

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.

Exopolysaccharides Producing Bacteria: A Review

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.

Exploring the potential of Halomonas levan and its derivatives as active ingredients in cosmeceutical and skin regenerating formulations

Demand on natural products that contain biological ingredients mimicking growth factors and cytokines made natural polysaccharides popular in pharmaceutical and cosmetic industries. Levan is the β-(2-6) linked, nontoxic, biocompatible, water-soluble, film former fructan polymer that has diverse applications in pharmacy and cosmeceutical industries with its moisturizing, whitening, anti-irritant, anti-aging and slimming activities. Driven by the limited reports on few structurally similar levan polymers, this study presents the first systematic investigation on the effects of structurally different extremophilic Halomonas levan polysaccharides on human skin epidermis cells. In-vitro experiments with microbially produced linear Halomonas levan (HL), its hydrolyzed, (hHL) and sulfonated (ShHL) derivatives as well as enzymatically produced branched levan (EL) revealed increased keratinocyte and fibroblast proliferation (113-118 %), improved skin barrier function through induced expressions of involucrin (2.0 and 6.43 fold changes for HL and EL) and filaggrin (1.74 and 3.89 fold changes for hHL and ShHL) genes and increased type I collagen (2.63 for ShHL) and hyaluronan synthase 3 (1.41 for HL) gene expressions together with fast wound healing ability within 24 h (100 %, HL) on 2D wound models clearly showed that HL and its derivatives have high potential to be used as natural active ingredients in cosmeceutical and skin regenerating formulations.

Characterization of levansucrase produced by novel Bacillus siamensis and optimization of culture condition for levan biosynthesis

Levan has attracted interest due to the potential health benefits associated with its prebiotic, biological, and functional properties. However, the production of levan is expensive due to its high resource requirements. With the growing demand for levan, it is vital to determine suitable cultivation condition for its production and reduce costs accordingly. The present study characterized the enzyme levansucrase produced by a novel strain of Bacillus siamensis and optimized the conditions for the biosynthesis of levansucrase and levan. The crude levansucrase enzyme production by B. siamensis was induced at a specific temperature in a medium containing different concentrations of sucrose, fructose, and glucose to evaluate transfructosylation and hydrolysis activities. Crude levansucrase significantly increased transfructosylation relative to hydrolysis activity at 37 °C in a medium containing 20% (w/v) sucrose. Both transfructosylation and hydrolysis activities were inhibited in glucose and fructose containing medium. Purification and characterization of the levansucrase were performed by precipitating the enzyme with ammonium sulfate solution, purified anion-exchange chromatography, and analyzed by Sodium Dodecyl Sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The results showed the molecular weight of the enzyme to be approximately 30 kDa with specific activity at 15.95 U/mg, corresponding to a protein purification efficiency of 11.47 and a yield of 78.75%. The optimal culture condition for the purified-levansucrase activity for levan biosynthesis was obtained at 37 °C after 48 h, at pH 6.0 in 50 mM phosphate buffer and 20% (w/v) sucrose. The study demonstrated the optimized condition for levan biosynthesis utilizing the B. siamensis that can serve as a model for various commercial and industrial applications for efficient levan production.

Application of Levan-Rich Digestate Extract in the Production of Safe-to-Use and Functional Natural Body Wash Cosmetics

The study focused on the evaluation of the possibility of using a levan-rich digestate extract in the production of safe and functional body wash cosmetics. Model shower gels were designed and formulated on the basis of raw materials of natural origin. Prepared prototypes contained various extract concentrations (16.7; 33; 50%). A gel without extract was used as a reference. The samples were evaluated for their safety in use and functionality. The results showed that the use of high-concentration levan-rich digestate extract in a shower gel resulted in a significant reduction in the negative impact on the skin. For example, the zein value decreased by over 50% in relation to the preparation without the extract. An over 40% reduction in the emulsifying capacity of hydrophobic substances was also demonstrated, which reduces skin dryness after the washing process. However, the presence of the extract did not significantly affect the parameters related to functionality. Overall, it was indicated that levan-rich digestate extract can be successfully used as a valuable ingredient in natural cleansing cosmetics.

Novel levan/bentonite/essential oil films: characterization and antimicrobial activity

Paenibacillus polymyxa is a microorganism used for the production of carbohydrate biopolymer levan in this work. Film samples were prepared with different contents of levan/bentonite. Film samples were evaluated for thickness, water vapor permeability, tensile strength and elongation properties. The most suitable film composite was chosen to evaluate antimicrobial activity. Antimicrobial properties were determined on different microorganisms by adding calendula oil, citronella oil, lemon oil, tamanu oil, peppermint (medical peppermint) oil in varying amounts to the film samples. The highest activity of levan/bentonite/oil composite film on microorganisms was measured with a diameter of 40 mm on Candida albicans in the composition of 0.5 mL of film content +1.5 mL of peppermint (medical peppermint) oil. This high antimicrobial activity film composite was characterized by TGA and SEM. It was made with levan/bentonite and peppermint oil, and the determination of antimicrobial effects of this film composite was reported for the first time. The bio-degradable film obtained has a high potential for use in different areas, especially in food packaging.

Targeted Hybrid Nanocarriers as a System Enhancing the Skin Structure

The skin is constantly exposed to external and internal factors that disturb its function. In this work, two nanosystems-levan nanoparticles and a surfactin-stabilized nanoemulsion were preserved (tested for microbial growth) and characterized (size, polydispersity, Zeta potential, and stability). The nanosystems were introduced in the model formulations-cream, tonic, and gel, and confirmed by TEM. The analysis showed that nanoemulsion has a spherical morphology and size 220-300 nm, while levan nanoparticles had irregular shapes independently of the use of matrix and with particle size (130-260 nm). Additionally, we examined the antiradical effect of levan nanoparticles and nanoemulsion in the prototype of formulations by scavenging DPPH (2,2-diphenyl-1-picrylhydrazyl; EPR spectroscopy). The model cream with both nanosystems and the whole range of products with nanosystems were evaluated in vivo for hydration, elasticity, smoothness, wrinkles and vascular lesions, discoloration, respectively. The cream improved skin condition in all tested parameters in at least 50% of volunteers. The use of more comprehensive care, additionally consisting of a tonic and gel, reduced the previously existing skin discoloration to 10.42 ± 0.58%. The presented prototype formulations are promising in improving skin conditions.

Biomedical Applications of Bacterial Exopolysaccharides: A Review

Bacterial exopolysaccharides (EPSs) are an essential group of compounds secreted by bacteria. These versatile EPSs are utilized individually or in combination with different materials for a broad range of biomedical field functions. The various applications can be explained by the vast number of derivatives with useful properties that can be controlled. This review offers insight on the current research trend of nine commonly used EPSs, their biosynthesis pathways, their characteristics, and the biomedical applications of these relevant bioproducts.

Structural elucidation and cytotoxic analysis of a fructan based biopolymer produced extracellularly by Zymomonas mobilis KIBGE-IB14

Fructan based biopolymers have been extensively characterized and explored for their potential applications. Linear chained biopolymers, like levan-type fructan, have gained attention because they have exhibited unconventional stretchable and unbendable properties along with biodegradable and biocompatible nature. Current study deals with the chemical characterization and cytotoxic analysis of fructose based exopolysaccharide that was extracellularly produced by an indigenously isolated bacterial species (Zymomonas mobilis KIBGE-IB14). Maximum yield of exopolysaccharide (44.7 gL^-1) was attained after 72 h of incubation at 30 °C under shaking conditions (180 rpm) when the culture medium was supplemented with 150.0 gL^-1 of sucrose as a sole carbon source. This exopolysaccharide displayed high water solubility index (96.0%) with low water holding capacity (17.0%) and an intrinsic viscosity of about 0.447 dL g^-1. This biopolymer exhibited a characteristic linear homopolysaccharide structure of levan when characterized using Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (NMR) spectroscopy (¹H, ¹³C, TOCSY and NOESY) while, Atomic Force Microscopy (AFM) revealed its pointed and thorny structure. The decomposition temperature of levan was approximately 245 °C as revealed by Thermal Gravimetric Analysis (TGA). X-Ray Diffraction (XRD) results revealed its amorphous nature with crystalline phase. Cytotoxicity of different concentrations of levan was investigated against mouse fibroblast cell lines by measuring their cellular metabolic activity and it was noticed that a higher concentration of levan (2.0 mg ml^-1) permitted the normal cell growth of NIH/3T3 cell lines. This non-cytotoxic and biocompatible nature suggests that this levan has the capability to be utilized in food and drug-based formulations as it exhibited biomedical potential.

Structural elucidation and interfacial properties of a levan isolated from Bacillus mojavensis

A strain with high exopolysaccharide (EPS) production was isolated from soil and identified as Bacillus mojavensis based on the 16S rRNA gene sequencing and biochemical properties. The EPS produced simultaneously with the growth phase reached a maximum of 22 g/L after attaining a stationary phase with sucrose used as sole carbon source. B. mojavensis EPS (BM-EPS) was recovered, fractionated by ethanol precipitation and analysed by NMR and methylation analyses. The BM-EPS was found to be composed of (β2 → 6)-Fruf residues, characteristic of a levan, with an average molecular weight of 2.3 MDa. A homogeneous micro-porous and rough structure matrix was observed by SEM of the freeze-dried powdered sample. A concentration-dependent water-soluble nature was observed, with good water (5.3 g/g) and oil (36 g/g) holding capacities. The levan displayed good emulsification activity with excellent stability against food grade oil, thus favoring it as a promising emulsifying agent to food industries.

Polysaccharides catabolism by the human gut bacterium -Bacteroides thetaiotaomicron: advances and perspectives

In recent years, the degradation processes of polysaccharides by human gut microbiota are receiving considerable attention due to the discoveries of the powerful function of gut microbiota. Gut microbiota has developed a sensitive, accurate, and complex system for sensing, capturing, and degrading different polysaccharides. Among the gut microbiota, Bacteroides thetaiotaomicron, a representative species of Bacteroides, is considered as the best degrader of polysaccharides and a potential probiotic in pharmaceutical and food industries. Here, we summarize the degradation system of B. thetaiotaomicron and the degradation pathways of different polysaccharides by B. thetaiotaomicron. We also describe a technical route for investigating a specific polysaccharide degradation pathway by human gut bacteria. In addition, we also provide the future perspectives in the development of novel polysaccharides or oligosaccharides drugs, precision microbiology medicine, and personalized nutrition.