Gel properties of xanthan containing a single repeating unit with saturated pyruvate produced by an engineered Xanthomonas campestris CGMCC 15155

Comprehensive rheological analysis of structurally related acetan-like heteroexopolysaccharides from two Kozakia baliensis strains in surfactants and galactomannan blends

Natural biopolymers become increasingly attractive as bio-based alternatives to petrol-based rheological modifiers, especially in personal care applications. However, many polysaccharides exhibit undesired properties in cosmetic applications such as limited viscosifying characteristics, unpleasant sensory properties, or incompatibility with certain formulation compounds. Here, a comprehensive rheological analysis of non-decorated acetan-like heteroexopolysaccharides derived from two Kozakia baliensis strains was performed in selected surfactant formulations. The results were compared to native xanthan gum and a genetically engineered xanthan variant, Xan∆gumFGL, which lacks any acetyl- and pyruvyl moieties and whose rheological properties are unaffected by saline environments. All four polysaccharides displayed a highly similar rheological performance in the non-ionic surfactant lauryl glucoside, while the rheological properties differed in amphoteric and anionic surfactants cocamidopropyl betaine and sodium laureth sulfate due to minor changes in side chain composition. Polysaccharide precipitation was observed in the presence of the cationic surfactant. Nevertheless, the native heteroexopolysaccharide derived from K. baliensis LMG 27018 shows significant potential as a salt-independent rheological modifier compared to the genetically engineered Xan∆gumFGL variant. In addition, blends of heteroexopolysaccharides from K. baliensis and several galactomannans displayed synergistic effects which were comparable to native xanthan gum-galactomannan blends. This study shows that heteroexopolysaccharides of K. baliensis are capable of further extending the portfolio of bio-based rheological modifiers.

Recent advances in modifications of exudate gums: Functional properties and applications

Gums are high-molecular-weight compounds with hydrophobic or hydrophilic characteristics, which are mainly comprised of complex carbohydrates called polysaccharides, often associated with proteins and minerals. Various innovative modification techniques are utilized, including ultrasound-assisted and microwave-assisted techniques, enzymatic alterations, electrospinning, irradiation, and amalgamation process. These methods advance the process, reducing processing times and energy consumption while maintaining the quality of the modified gums. Enzymes like xanthan lyases, xanthanase, and cellulase can selectively modify exudate gums, altering their structure to enhance their properties. This precise enzymatic approach allows for the use of exudate gums for specific applications. Exudate gums have been employed in nanotechnology applications through techniques like electrospinning. This enables the production of nanoparticles and nanofibers with improved properties, making them suitable for the drug delivery system, tissue engineering, active and intelligient food packaging. The resulting modified exudate gums exhibit improved rheological, emulsifying, gelling, and other functional properties, which expand their potential applications. This paper discusses novel applications of these modified gums in the pharmaceutical, food, and industrial sectors. The ever-evolving field presents diverse opportunities for sustainable innovation across these sectors.

Production of Bacterial Exopolysaccharides: Xanthan and Bacterial Cellulose

Recently, degradable biopolymers have become increasingly important as potential environmentally friendly biomaterials, providing a wide range of applications in various fields. Bacterial exopolysaccharides (EPSs) are biomacromolecules, which due to their unique properties have found applications in biomedicine, foodstuff, textiles, cosmetics, petroleum, pharmaceuticals, nanoelectronics, and environmental remediation. One of the important commercial polysaccharides produced on an industrial scale is xanthan. In recent years, the range of its application has expanded significantly. Bacterial cellulose (BC) is another unique EPS with a rapidly increasing range of applications. Due to the great prospects for their practical application, the development of their highly efficient production remains an important task. The present review summarizes the strategies for the cost-effective production of such important biomacromolecules as xanthan and BC and demonstrates for the first time common approaches to their efficient production and to obtaining new functional materials for a wide range of applications, including wound healing, drug delivery, tissue engineering, environmental remediation, nanoelectronics, and 3D bioprinting. In the end, we discuss present limitations of xanthan and BC production and the line of future research.

Structure-property relationship in the evaluation of xanthan gum functionality for oral suspensions and tablets

The functional properties of xanthan gum (XG) in pharmaceutical preparations depend on its rheological properties, which inevitably rely on its molecular structure. Hence, this work investigated the relationship between the molecular structure of XG and its rheological properties and functional characteristics, and revealed the structural factors influencing the XG functionalities in oral suspensions and matrix tablets. Primarily, the molecular structures of four commercial XG products were characterized by infrared spectroscopy, differential scanning calorimetry and measuring the monosaccharide composition, average molecular weight, and pyruvate and acetyl contents. Furthermore, the flow behavior and viscoelasticity of XG solutions, the viscoelasticity of XG hydrogels, and XG combinations (XGC, aqueous solution containing XG, liquid glucose, and glycerin) were investigated. Finally, the dissolution time of XGC and the swelling and erosion properties of the XG matrix were studied to evaluate XG functionality in oral suspensions and matrix tablets, respectively. Results showed that the polydispersity of molecular weight and the pyruvate content affected the functionality and performance of XG in suspension and tablet forms. The higher polydispersity and pyruvate content of XG improved the hydrogel strength, which led to a longer dissolution time of XGC and a higher swelling extent of the XG matrix but a slower erosion rate.

Physicochemical properties and in vitro digestion behavior of a new bioactive Tremella fuciformis gum

A new easy-dissolved Tremella fuciformis gum (TFG) from fruiting body was investigated in detail from three aspects: physicochemical characteristics, rheological behavior and in vitro digestion behavior. The results showed that TFG consisted of 73.9% polysaccharides, exhibiting easy solubility in water and good colloidal characteristics and stability. The physical and chemical treatments could decrease the apparent viscosity of TFG solution. The antioxidation activity of TFG remained constant at each static in vitro digestion phase, revealing that this gum could be used as a potential food thickener and antioxidant. The digestion behavior of TFG was also determined using a dynamic in vitro digestive system, DIVRS-II. The results demonstrated that the digestion behavior of TFG should be attributed to the morphology of digestive tracts, continuous secreting and continuous emptying. The antitussive effect of TFG was related to the increase in serum IL-10 content.

Improved color stability of anthocyanins in the presence of ascorbic acid with the combination of rosmarinic acid and xanthan gum

This study investigated the protective effect and mechanism of action of combined use of rosmarinic acid (RA) and xanthan gum (XG) on the stability of anthocyanins (ACNs) in the presence of l-ascorbic acid (pH 3.0). The addition of RA and XG, alone and in combination, significantly enhanced the color stability of ACNs, and the combined use of RA and XG showed the best effect. FTIR, 1H NMR, AFM and computational molecular simulation analyses revealed that the improvement in ACN stability following the combined addition of RA and XG was due to intermolecular interactions such as hydrogen bonding and van der Waals forces. In the ACN-RA-XG ternary complexes, XG had stronger binding interactions with ACNs than RA. Our findings provide a valuable potential to enhance the stability of ACNs in the presence of ascorbic acid with the combined use of RA and XG.

A review of the enzymatic, physical, and chemical modification techniques of xanthan gum

Xanthan gum (XG), a bacterial polysaccharide has numerous valuable characteristics in the food, biomedical, pharmaceuticals, and agriculture sector. However, XG has also its particular limitations such as its vulnerability to microbial contamination, inadequate mechanical and thermal stability, unusable viscosity, and poor water solubility. Therefore, XG's structure and conformation need to be modified enzymatically, chemically, or physically to improve its optimistic features and decrease the formation of crystals, increase antioxidant ability, and radical scavenging activity. We have found out different means to modify XG and elaborate the importance and significance of the modified structure of XG. In this review, different enzymes are reviewed for XG degradation, which modifies their structure from different points (main chain or side chain). This article also reviews various physical methods (ultrasound, shear, pressure, sonication, annealing, and heat treatments) based on prevailing publications to alter XG conformation and produce low molecular weight (LMW) and less viscous end-product. Moreover, some chemical means are also discussed that result in modified XG through crosslinking, grafting, acetylation, pyruvation, as well as by applying different chemical agents. Overall, the current progress on XG degradation is very auspicious to develop a new molecule with considerable uses, in various industries with future assessments.

Thermostable and rheological properties of natural and genetically engineered xanthan gums in different solutions at high temperature

Thermostability is an important indicator to evaluate xanthan applied in the oilfield industry. Besides reductive agents, salts, and pH, the inherent primary structure is also an important determinant of thermostability. In this work, the thermal conformational transition and degradation of natural xanthan XG and variants XG-A0, XG-AA, and XG-0P dissolved in different solvents were compared. Acetylated XG-A0 and XG-AA both showed the highest initial conformational transition temperature (Tm₀) in distilled water, NaCl, and CaCl₂ brines. Additionally, the variant XG-A0 dissolved in water was more thermostable although its acetyl group was hydrolyzed easily after a hot-rolling test at 110 °C. Thermostability could be reinforced by adding antioxidant Na₂SO₃ and saturated NaCl through improving Tm₀ value or inhibiting degradation of the molecular chain and acyl groups. Furthermore, pyruvyl-rich XG-0P dissolved in saturated NaCl showing multi-stranded helix structure was also stable after a hot-rolling process. Therefore, xanthan variants, as biological products, will have broader application potential in the oilfield industry.

Bacterial exopolysaccharides: Chemical structures, gene clusters and genetic engineering

In recent decades, the composition, structure, biosynthesis, and function of bacterial extracellular polysaccharides (EPS) have been extensively studied. EPS are synthesized through different biosynthetic pathways. The genes responsible for EPS synthesis are usually clustered on the genome or large plasmids of bacteria. Generally, different EPS synthesis gene clusters direct the synthesis of EPS with different chemical structures and biological activities. A better understanding of the gene functions involved in EPS biosynthesis is critical for the production of EPS with special biological activities. Genetic engineering methods are usually used to study EPS synthesis related genes. This review organizes the available information on EPS, including their structures, synthesis of related genes, and highlights the research progress of modifying EPS gene clusters through gene-editing methods.

A Brief Review of Edible Coating Materials for the Microencapsulation of Probiotics

The consumption of probiotics has been associated with a wide range of health benefits for consumers. Products containing probiotics need to have effective delivery of the microorganisms for their consumption to translate into benefits to the consumer. In the last few years, the microencapsulation of probiotic microorganisms has gained interest as a method to improve the delivery of probiotics in the host as well as extending the shelf life of probiotic-containing products. The microencapsulation of probiotics presents several aspects to be considered, such as the type of probiotic microorganisms, the methods of encapsulation, and the coating materials. The aim of this review is to present an updated overview of the most recent and common coating materials used for the microencapsulation of probiotics, as well as the involved techniques and the results of research studies, providing a useful knowledge basis to identify challenges, opportunities, and future trends around coating materials involved in the probiotic microencapsulation.