Bacterial polysaccharides-A big source for prebiotics and therapeutics

A review of the fungal polysaccharides as natural biopolymers: Current applications and future perspective

As a unique natural resource, fungi are a sustainable source of lipids, polysaccharides, vitamins, proteins, and other nutrients. As a result, they have beneficial medicinal and nutritional properties. Polysaccharides are among the most significant bioactive components found in fungi. Increasing research has revealed that fungal polysaccharides (FPS) contain a variety of bioactivities, including antitumor, antioxidant, immunomodulatory, anti-inflammatory, hepatoprotective, cardioprotective, and anti-aging properties. However, the exact knowledge about FPS and their applications related to their future possibilities must be thoroughly examined to enhance a better understanding of this sustainable biopolymer source. Therefore, FPS' biological applications and their role in the food and feed industry, agriculture, and cosmetics applications were all discussed in this work. In addition, this review highlighted the mode of action of FPS on human diseases by regulating gut microbiota and discussed the mechanism of FPS as antioxidants in the living cell. The structure-activity connections of FPS were also highlighted and explored. Moreover, future perspectives were listed to pave the way for future studies of FPS applications. Hence, this study can be a scientific foundation for future FPS research and industrial applications.

Restoration of Lactobacillus johnsonii and Enterococcus faecalis Caused the Elimination of Tritrichomonas sp. in a Model of Antibiotic-Induced Dysbiosis

Inflammatory bowel disease (IBD) is a multifactorial disease involving the interaction of the gut microbiota, genes, host immunity, and environmental factors. Dysbiosis in IBD is associated with pathobiont proliferation, so targeted antibiotic therapy is a rational strategy. When restoring the microbiota with probiotics, it is necessary to take into account the mutual influence of co-cultivated microorganisms, as the microbiota is a dynamic community of species that mediates homeostasis and physiological processes in the intestine. The aim of our study was to investigate the recovery efficacy of two potential probiotic bacteria, L. johnsonii and E. faecalis, in Muc2-/- mice with impaired mucosal layer. Two approaches were used to determine the efficacy of probiotic supplementation in mice with dysbiosis caused by mucin-2 deficiency: bacterial seeding on selective media and real-time PCR analysis. The recovery time and the type of probiotic bacteria relocated affected only the number of E. faecalis. A significant positive correlation was found between colony-forming unit (CFU) and the amount of E. faecalis DNA in the group that was replanted with probiotic E. faecalis. As for L. johnsonii, it could be restored to its original level even without any additional bacteria supplementation after two weeks. Interestingly, the treatment of mice with L. johnsonii caused a decrease in the amount of E. faecalis. Furthermore, either L. johnsonii or E. faecalis treatment eliminated protozoan overgrowth caused by antibiotic administration.

A Long-Chain Dextran Produced by Weissella cibaria Boosts the Diversity of Health-Related Gut Microbes Ex Vivo

Long-chain dextrans are α-glucans that can be produced by lactic acid bacteria. NextDextTM, a specific long-chain dextran with a high degree of polymerisation, produced using Weissella cibaria, was recently shown to exert prebiotic potential in vitro. In this study, the ex vivo SIFR® technology, recently validated to provide predictive insights into gut microbiome modulation down to the species level, was used to investigate the effects of this long-chain dextran on the gut microbiota of six human adults that altogether covered different enterotypes. A novel community modulation score (CMS) was introduced based on the strength of quantitative 16S rRNA gene sequencing and the highly controlled ex vivo conditions. This CMS overcomes the limitations of traditional α-diversity indices and its application in the current study revealed that dextran is a potent booster of microbial diversity compared to the reference prebiotic inulin (IN). Long-chain dextran not only exerted bifidogenic effects but also consistently promoted Bacteroides spp., Parabacteroides distasonis and butyrate-producing species like Faecalibacterium prausnitzii and Anaerobutyricum hallii. Further, long-chain dextran treatment resulted in lower gas production compared to IN, suggesting that long-chain dextran could be better tolerated. The additional increase in Bacteroides for dextran compared to IN is likely related to the higher propionate:acetate ratio, attributing potential to long-chain dextran for improving metabolic health and weight management. Moreover, the stimulation of butyrate by dextran suggests its potential for improving gut barrier function and inflammation. Overall, this study provides a novel tool for assessing gut microbial diversity ex vivo and positions long-chain dextran as a substrate that has unique microbial diversity enhancing properties.

Effect of monosaccharide composition and proportion on the bioactivity of polysaccharides: A review

Polysaccharides have been widely used in pharmaceutical and food industries due to their diverse bioactivity, high safety, and few or no side effects. However, inability to quickly produce, screen, and synthesize bioactive polysaccharides is the limiting factor for their development and application. Structural features determine and influence the bioactivity of polysaccharides. Among them, monosaccharide is the basic unit of polysaccharide, which not only affects electrification, functional group, and bioactivity of polysaccharide but also is one of the simplest polysaccharide indexes to be detected. At present, effects of monosaccharide composition and proportion on anti-inflammatory, antioxidant, antitumor, immunomodulatory, antibacterial, and prebiotic activities of polysaccharides are reviewed. Further problems need to be considered during regulation and analysis of monosaccharide composition and proportion of polysaccharides. Overall, present work will provide help and reference for production, development, and structure-function investigation of polysaccharides based on their monosaccharide.

The role of the glycome in symbiotic host-microbe interactions

Glycosylation plays a crucial role in many aspects of cell biology, including cellular and organismal integrity, structure-and-function of many glycosylated molecules in the cell, signal transduction, development, cancer, and in a number of diseases. Besides, at the inter-organismal level of interaction, a variety of glycosylated molecules are involved in the host-microbiota recognition and initiation of downstream signalling cascades depending on the outcomes of the glycome-mediated ascertainment. The role of glycosylation in host-microbe interactions is better elaborated within the context of virulence and pathogenicity in bacterial infection processes but the symbiotic host-microbe relationships also involve substantive glycome-mediated interactions. The works in the latter field have been reviewed to a much lesser extent, and the main aim of this mini-review is to compensate for this deficiency and summarise the role of glycomics in host-microbe symbiotic interactions.

Exploring the Role of Green Microbes in Sustainable Bioproduction of Biodegradable Polymers

Research efforts have shifted to creating biodegradable polymers to offset the harmful environmental impacts associated with the accumulation of non-degradable synthetic polymers in the environment. This review presents a comprehensive examination of the role of green microbes in fostering sustainable bioproduction of these environment-friendly polymers. Green microbes, primarily algae and cyanobacteria, have emerged as promising bio-factories due to their ability to capture carbon dioxide and utilize solar energy efficiently. It further discusses the metabolic pathways harnessed for the synthesis of biopolymers such as polyhydroxyalkanoates (PHAs) and the potential for genetic engineering to augment their production yields. Additionally, the techno-economic feasibility of using green microbes, challenges associated with the up-scaling of biopolymer production, and potential solutions are elaborated upon. With the twin goals of environmental protection and economic viability, green microbes pave the way for a sustainable polymer industry.

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.

Characterization and bioactivities of exopolysaccharide produced from Azotobacter salinestris EPS-AZ-6

This study involved the extraction of an exopolysaccharide (EPS) from Azotobacter salinestris AZ-6, which was isolated from soil cultivated with leguminous plants. In a medium devoid of nitrogen, the AZ-6 strain displayed a maximum EPS yield of 1.1 g/l and the highest relative viscosity value of 3.4. The homogeneity of the polymer was demonstrated by the average molecular weight of 1.61 × 106 Da and a retention time of 17.211 min for levan. The presence of characteristic functional groups and structural units of carbohydrate polymers has been confirmed through spectroscopic analyses utilizing Fourier-transform infrared (FT-IR) and nuclear magnetic resonance (NMR) techniques. Thermogravimetric analysis (TGA) revealed a noteworthy decrease in weight (74 %) in the temperature range spanning from 260 to 350 °C. X-ray diffraction (XRD) was utilized to verify the crystalline and amorphous characteristics of EPS-AZ-6. The EPS-AZ-6 exhibited significant cytotoxicity against the MCF-7 tumor cell line, as evidenced by an IC50 value of 6.39 ± 0.05 μg/ml. It also demonstrated a moderate degree of cytotoxicity towards HepG-2 cell line, as indicated by an IC50 value of 29.79 ± 0.41 μg/ml. EPS-AZ-6 exhibited potent antioxidant and in vitro antibacterial properties. These characteristics suggest the potential application value of EPS-AZ-6 in the food industry and pharmaceutical applications.

Marine Microbial Polysaccharides: An Untapped Resource for Biotechnological Applications

As the largest habitat on Earth, the marine environment harbors various microorganisms of biotechnological potential. Indeed, microbial compounds, especially polysaccharides from marine species, have been attracting much attention for their applications within the medical, pharmaceutical, food, and other industries, with such interest largely stemming from the extensive structural and functional diversity displayed by these natural polymers. At the same time, the extreme conditions within the aquatic ecosystem (e.g., temperature, pH, salinity) may not only induce microorganisms to develop a unique metabolism but may also increase the likelihood of isolating novel polysaccharides with previously unreported characteristics. However, despite their potential, only a few microbial polysaccharides have actually reached the market, with even fewer being of marine origin. Through a synthesis of relevant literature, this review seeks to provide an overview of marine microbial polysaccharides, including their unique characteristics. In particular, their suitability for specific biotechnological applications and recent progress made will be highlighted before discussing the challenges that currently limit their study as well as their potential for wider applications. It is expected that this review will help to guide future research in the field of microbial polysaccharides, especially those of marine origin.

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.

RGI-Type Pectic Polysaccharides Modulate Gut Microbiota in a Molecular Weight-Dependent Manner In Vitro

In this study, the fermentation characteristics of high rhamnogalacturonan I pectic polysaccharides (RGI) and free-radical degraded RGI (DRGI) were evaluated by a human fecal batch-fermentation model, and their structural properties were also investigated. As a result, the M_w of RGI decreased from 246.8 to 11.6 kDa, and the branches were broken dramatically. Fermentation showed that RGI degraded faster and produced more acetate and propionate than DRGI. Both of them reduced the Firmicutes/Bacteroidetes ratio and promoted the development of Bacteroides, Bifidobacterium, and Lactobacillus, bringing benefits to the gut ecosystem. However, the composition and metabolic pathways of the microbiota in RGI and DRGI were different. Most of the dominant bacteria of RGI (such as [Eubacterium]_eligens_group) participated in carbohydrate utilization, leading to better performance in glucolipid metabolism and energy metabolism. This work elucidated that large molecular weight matters in the gut microbiota modulatory effect of RGI-type pectic polysaccharides in vitro.