Structural features of microbial exopolysaccharides in relation to their antioxidant activity

In Vitro and In Vivo Interventions Reveal the Health Benefits of Levan-Type Exopolysaccharide Produced by a Fish Gut Isolate Lactobacillus reuteri FW2

Microorganisms synthesize diverse types of exopolysaccharides (EPSs). EPSs with varying structural and physical properties can demonstrate unique health benefits, which allow for their tailored applications as functional foods such as prebiotics. Levan, a fructose-based EPS, is gaining considerable attention as an effective prebiotic to support the growth of beneficial gut bacteria. Consequently, this enhances digestive health, boosts the immune system, and reduces the risk of chronic diseases. Unfortunately, limited studies are available on levan-type EPSs to demonstrate their role as prebiotics. Therefore, in this study, we conducted in vitro and in vivo experiments, concerning intestinal cell integrity and metabolic syndrome, to assess the therapeutic potential of levan derived from Lactobacillus reuteri FW2. The in vitro experimental results revealed that levan improved the survival of impaired HT-29 epithelial cells of the intestine and also exerted antioxidant effects. In the in vivo experiments, mice fed with levan-supplemented feed exhibited low body weight gain, blood glucose, and serum cholesterol levels compared to the control group. These findings highlight the biotherapeutic potential of L. reuteri FW2-derived levan for improving metabolic syndrome and its associated aspects. It also signifies the need for a further detailed investigation based on clinical trials to include levan in dietary supplements for improved health and well-being.

Valorization of pineapple (ANANAS comosus) peel waste for levan production: Assessment of biological activities

Levan canopies a pivotal role in all the emerging sectors owing to its non-toxic and biodegradable nature. However, their expensive production impeded their commercialization and made them uneconomical. Hence the current work is focused on harnessing the pineapple peel as a viable substrate for bacterial fermentation to promote levan production. Bacterial strains isolated from different sites was assessed for levansucrase activity among which L10 strain an isolate from sugarcane soil had maximum levansucrase activity was further screened for levan production and identified as Bacillus tequilensis through molecular characterization. The identified bacterium was screened for levan production from various minimal medium of which MM4 yielded maximum and the same has been reconstituted with different proportion of pineapple peel hydrolysate. Medium with 30 % peel hydrolysate exhibited maximum levan and biomass production of 1.8 g/L and 3.23 g/L respectively. The harvested EPS was characterized by FTIR, NMR, HPLC, and GPC to elucidate the functional groups and monomeric composition which similar with the previous researches. Anticancerous activity of levan towards MDA-MB-231 cell line was apparent with the down regulation of the anti-apoptotic gene Bcl2 and upregulation the apoptosis genes comparable to cisplatin. Flow cytometry analysis reveals that the cell cycle arrests crop up at G2/M biopolymers whereas cisplatin arrest at G0/G1 biopolymers.

Production optimization and antioxidant potential of exopolysaccharide produced by a moderately halophilic bacterium Virgibacillus dokdonensis VITP14

This study aimed to enhance the extracellular polymeric substances (EPS) production of Virgibacillus dokdonensis VITP14 and explore its antioxidant potential. EPS and biomass production by VITP14 strain were studied under different culture parameters and media compositions using one factor at a time method. Among different nutrient sources, glucose and peptone were identified as suitable carbon and nitrogen sources. Furthermore, the maximum EPS production was observed at 5% of inoculum size, 5 g/L of NaCl, and 96 h of fermentation. Response surface methodology was employed to augment EPS production and investigate the optimal levels of nutrient sources with their interaction. The strain was observed to produce actual maximum EPS of about 26.4 g/L for finalized optimum medium containing glucose 20 g/L, peptone 10 g/L, and NaCl 50 g/L while the predicted maximum EPS was 26.5 g/L. There was a nine fold increase in EPS production after optimization study. Additionally, EPS has exhibited significant scavenging, reducing, and chelating potential (>85%) at their higher concentration. This study imparts valuable insights into optimizing moderately halophilic bacterial EPS production and evaluating its natural antioxidant properties. According to findings, V. dokdonensis VITP14 was a promising isolate that will provide significant benefits to biopolymer producing industries.

Bacterial exopolysaccharides: Characteristics and antioxidant mechanism

Bacterial exopolysaccharides (EPS) are secondary metabolites of microorganisms which play important roles in adhesion, protection, biofilm formation, and as a source of nutrition. Compared with polysaccharides obtained from animal and plant species, bacterial polysaccharides have significant advantages in terms of production cost and large-scale production due to their abundant metabolic pathways and efficient polysaccharide production capacity. Most extracellular polysaccharides are water-soluble, and some are insoluble, such as bacterial cellulose. Some soluble bacterial EPS also have biological activities such as anticancer, antioxidant, antibacterial and immunomodulatory activities. These biological activities are mainly affected by the molecular weight, monosaccharide type, composition and structure of EPS. In recent years, bacterial EPS are considered as novel functional polysaccharides with important application prospects, especially in free radical scavenging and antioxidation. This review focuses on the characteristics of bacterial EPS, their ability to scavenge free radicals and their corresponding antioxidant mechanisms, and summarizes the relationship between different structures (such as monosaccharide composition, functional groups, molecular weight, etc.) and antioxidant activities. It provides a new idea for the development of more bioactive bacterial EPS antioxidants, points out a new direction for the commercial production of natural, safe and economical polysaccharide drugs and health products.

Optimization of welan gum extraction and purification using lysozyme and alkaline protease

Welan gum, a natural polysaccharide produced by Sphingomonas sp. ATCC 31555, has attracted considerable attention in the scientific community due to its desirable properties. However, challenges, such as high viscosity, residual bacterial cells, carotenoids, and protein complexation, hinder the widespread application of welan gum. In this study, we established a method for the extraction and purification of welan gum using a synergistic approach with lysozyme and alkaline protease. Lysozyme hydrolysis conditions were optimized by applying response surface methodology, and the best results for bacterial cell removal were achieved at 11 000 U/g, 44 °C, and pH 9 after 3 h of treatment. Subsequently, we evaluated protein hydrolysis through computer simulation and identified alkaline protease as the most suitable enzyme. Through experimental investigations, we found that the optimal conditions for alkaline protease hydrolysis were 7500 U/g, 50 °C, pH 10, and 600 rpm. These conditions resulted in a sugar recovery rate of 76.1%, carotenoid removal rate of 89.5%, bacterial removal rate of 95.2%, and protein removal rate of 87.3% after 3 h of hydrolysis. The purified welan gum exhibited high transparency and purity. Structural characterization and antioxidant activity evaluation revealed that enzymatically purified welan gum has potential application prospects. Our study provides valuable insights into the optimal method for the enzymatic extraction and purification of welan gum. Such a method is conducive to the development of the multiple potential applications of welan gum. KEY POINTS: • A novel process for the synergistic purification of welan gum using lysozyme and alkaline protease was established. • In silico virtual digestion was employed to select the purification enzyme. • Welan gum with high transparency and purity was obtained.

Unrevealing the potentialities in food formulations of a low-branched dextran from Leuconostoc mesenteroides

The search for novel exopolysaccharides (EPS) with targeted functionalities is currently a topic of great interest. This study aimed to investigate the chemical characteristics and technological properties of a novel EPS (named EPS_O) from Leuconostoc mesenteroides. EPS_O was a high-molecular-weight dextran (>6.68 × 105 g/mol) characterized by high water-holding capacity (785 ± 73%) and high water solubility index (about 99%). EPS_O in water (<30 mg/mL) formed viscous solutions, whereas at concentrations >30 mg/mL, it formed weak gels. Notably, lower concentrations (4-5 mg/mL) exhibited antimicrobial activity against various foodborne pathogens, antibiofilm activity against Listeria monocytogenes, and radical-scavenging activity. These properties are significant for maintaining food quality and promoting health. Based on these findings, EPS_O presents itself as a promising food ingredient that could elevate food quality and confer health benefits to consumers.

Characterization of a novel antioxidant exopolysaccharide from an intestinal-originated bacteria Bifidobacterium pseudocatenulatum Bi-OTA128

Microbial exopolysaccharides (EPSs) have attracted extensive attention for their biological functions in antioxidant activities. In this study, we characterized a novel EPS produced by Bifidobacterium pseudocatenulatum Bi-OTA128 which exhibited the highest antioxidant capacity compared to nine other ropy bacterial strains, achieving 76.50 % and 93.84 % in DPPH· and ABTS·+ scavenging activity, and ferric reducing power of 134.34 μM Fe2+. Complete genomic analysis identified an eps gene cluster involved in the EPS biosynthesis of Bi-OTA128 strain, which might be responsible for its ropy phenotype. The EPS was then isolated and purified by a DEAE-Sepharose Fast Flow column. A single elution part EPS128 was obtained with a recovery rate of 43.5 ± 1.78 % and a total carbohydrate content of 93.6 ± 0.76 %. Structural characterization showed that EPS128 comprised glucose, galactose, and rhamnose (molar ratio 4.0:1.2:1.1), featuring a putative complex backbone structure with four branched chains and an unusual acetyl group at O-2 of terminal rhamnose. Antioxidant assay in vitro indicated that EPS128 exhibited antioxidant potential with 50.52 % DPPH· and 65.40 % ABTS·+ scavenging activities, reaching 54.3 % and 70.44 % of the efficacy of standard Vitamin C at 2.0 mg/L. Furthermore, EPS128 showed protective effects against H2O2-induced oxidative stress in HepG2 cells by reducing cellular reactive oxygen species (ROS) and increasing cell viability. These findings present the first comprehensive report of an antioxidant EPS from B. pseudocatenulatum, highlighting its potential as a natural antioxidant for applications in the food industry and clinical settings.

Advances in characterization of probiotics and challenges in industrial application

An unbalanced diet and poor lifestyle are common reasons for numerous health complications in humans. Probiotics are known to provide substantial benefits to human health by producing several bioactive compounds, vitamins, short-chain fatty acids and short peptides. Diets that contain probiotics are limited to curd, yoghurt, kefir, kimchi, etc. However, exploring the identification of more potential probiotics and enhancing their commercial application to improve the nutritional quality would be a significant step to utilizing the maximum benefits. The complex evolution patterns among the probiotics are the hurdles in their characterization and adequate application in the industries and dairy products. This article has mainly discussed the molecular methods of characterization that are based on the analysis of ribosomal RNA, whole genome, and protein markers and profiles. It also has critically emphasized the emerging challenges in industrial applications of probiotics.

Star anise (Illicium verum Hook. F.) polysaccharides: Potential therapeutic management for obesity, hypertension, and diabetes

This study explores the extraction of polysaccharides from star anise (Illicium verum Hook. f.) with its anti-obesity, antihypertensive, antidiabetic, and antioxidant properties. The aim is to optimize the extraction conditions of star anise polysaccharides (SAP) utilizing propane alcohols-based deep eutectic solvents and microwave-assisted methods. The optimized conditions resulted in an extraction yield of 5.14%. The characteristics of acidic pectin-like SAP, including high viscosity (44.86 mPa s), high oil-holding capacity (14.39%), a high degree of esterification (72.53%), gel-like properties, highly amorphous, a high galacturonic acid concentration, and a highly branching size polysaccharide structure, significantly contribute to their potent inhibition of pancreatic lipase (86.67%), angiotensin-converting enzyme (73.47%), and α-glucosidase (82.33%) activities as well as to their antioxidant properties of azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS, 34.94%) and ferric ion reducing antioxidant power (FRAP, 0.56 mM FeSO4). Therefore, SAP could be used as a potential therapeutic agent for obesity, hypertension, and diabetes mellitus management.

Evaluation of antioxidant and anti-inflammatory properties of Lacticaseibacillus rhamnosus Ram12-derived exopolysaccharide in a D-galactose-induced liver injury mouse model

We investigated the antioxidant and anti-inflammatory properties of Lacticaseibacillus rhamnosus Ram12-derived EPSRam12 in a D-galactose-induced liver injury mouse model. Initially, EPSRam12 was characterized for its composition, molecular weight, and structural features. It was then administered orally to D-galactose-induced mice (which had received an intraperitoneal injection of D-galactose, 100 mg/kg body weight) at doses of 25 mg/kg (low dose) and 50 mg/kg (high dose) for 45 days. After treatment, biochemical markers, antioxidant status, cytokine levels, and liver inflammatory gene expression were evaluated. The results showed that EPSRam12 was a branched chain heteropolysaccharide comprising mannose, rhamnose, and arabinose monosaccharides with molecular weight of 2.6 million Daltons. EPSRam12, with its unique structural features such as hydroxyl and methyl groups, glycosidic bonds, and functional groups like carboxylates and sulfates, demonstrated promising bioactive properties. Administering EPSRam12 to D-galactose-induced mice resulted in a significant increase in antioxidant enzyme activity and a reduction in oxidative stress indicators. Additionally, it exhibited anti-inflammatory effects by modulating cytokine levels, lowering pro-inflammatory markers, and inhibiting key inflammatory pathways in the liver in a dose-dependent manner. Our findings underscore the potential of EPSRam12 as an effective antioxidant and anti-inflammatory agent, with promising applications in functional foods and pharmaceuticals.

Influence of flaxseed mucilage on the formation, composition, and properties of exopolysaccharides produced by different strains of lactic acid bacteria

Microorganisms produce a wide variety of polysaccharides. Due to biosafety considerations, lactic acid bacteria (LAB) are popular producers of exopolysaccharides (EPS) for various applications. In this study, we analyzed the composition and properties of EPS produced by L. delbrueckii ssp. bulgaricus and LAB from clover silage (L. fermentum AG8, L. plantarum AG9) after growth on Man, Rogosa, and Sharpe broth (MRS) and with the addition of flaxseed mucilage (FSM) using chromatography, microscopy, and biochemical methods. We found that adding 0.4 % FSM does not drastically alter the medium's rheology but substantially increases EPS yield (by 3.1 to 3.8 times) and modifies the composition and macrostructure of EPS, as well as changes the spatial organization of LAB cells. The presence of FSM led to the production of xylose- and glucose-enriched EPS, which also contained varying proportions of fucose, rhamnose, arabinose, mannose, glycosamines, and uronic acids, depending on the strain. Most EPS had a low molecular weight (up to 32 kDa), except for EPS produced by L. fermentum AG8 in FSM-containing medium, which had molecular weight of 163 kDa. All EPS exhibited a porous microstructure and demonstrated scavenging capacity for OH- and DPPH-radicals, as well as high levels of α-glucosidase and lipase inhibitory activities, even at low concentrations (<1 g·L-1 of EPS). These characteristics make them promising for use in functional food production and medicine.

Antioxidant Activities of Exopolysaccharides Extracts from Two Endemic Fungi from Patagonia

A great number of free radicals have a negative impact on the human body, and an increased interest in the identification of new natural molecules with antioxidant properties has emerged due to concerns about synthetic antioxidants. Here, the antioxidant effect of four exo-polysaccharides (EPS) extracts obtained from submerged cultivation of Nothophellinus andinopatagonicus and Pseudoinonotus crustosus (N and P, respectively) in two culture media (M1 and M2) at 2 concentrations (100 and 250 µg/ml) was studied; then, its relation with the chemical composition of the EPS was evaluated. To assess the antioxidant activities of the extracts, several in vitro assays were performed: DPPH and ABTS radical scavenging, ferric-reducing antioxidant power, chelating ability on ferrous ions, and inhibition of the lipid peroxidation. The concentrations tested here were much lower than those reported in previous works. Despite variations in chemical composition and monosaccharide profiles among the extracts, all demonstrated antioxidant activity, although the type of activity differed; only P-M1 exhibited a good antioxidant activity across all assays. This extract contained the highest proportion of phenolic compounds, and also displayed the highest radical scavenging activity. Although the utilization of polysaccharides as functional food ingredients remains limited, we propose P-M1 as a promising candidate for a nutraceutical product. Additionally, a formulation could be made with a combination of extracts to create an antioxidant-rich supplement. Additional research is needed to confirm our findings in a cellular environment and to elucidate the mechanisms that drive their antioxidant activities, ultimately facilitating their development and utilization as nutraceutical products.

Advances in Microbial Exopolysaccharides: Present and Future Applications

Microbial exopolysaccharides (EPSs) are receiving growing interest today, owing to their diversity in chemical structure and source, multiple functions, and immense potential applications in many food and non-food industries. Their health-promoting benefits for humans deserve particular attention because of their various biological activities and physiological functions. The aim of this paper is to provide a comprehensive review of microbial EPSs, covering (1) their chemical and biochemical diversity, including composition, biosynthesis, and bacterial sources belonging mainly to lactic acid bacteria (LAB) or probiotics; (2) their technological and analytical aspects, especially their production mode and characterization; (3) their biological and physiological aspects based on their activities and functions; and (4) their current and future uses in medical and pharmaceutical fields, particularly for their prebiotic, anticancer, and immunobiotic properties, as well as their applications in other industrial and agricultural sectors.

Functional characterization and biotechnological applications of exopolysaccharides produced by newly isolated Enterococcus hirae MLG3-25-1

This study investigated the potential applications of Enterococcus hirae MLG3-25-1 exopolysaccharides (EPS), with a focus on their isolation, identification, production, and functional characteristics. After the bacterial strain was cultured in De Man-Rogosa-Sharpe (MRS) medium containing 1% glucose at 37 °C, the EPS was refined, and the highest yield of 0.85 mg/mL was achieved at the 24-h incubation period. Enterococcus hirae MLG3-25-1 was found to be able to produce EPS. The study explored the microstructure of the EPS, which resembles polysaccharide sheets with smooth surfaces, through scanning electron microscope (SEM) analysis. Through Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) analysis, the chemical composition, aligning with glycosidic bond characteristics, has been deciphered. Furthermore, the antimicrobial and antibiofilm activities against pathogenic bacteria, particularly Bacillus sp., demonstrated potential applications in combating antibiotic resistance. The EPS exhibited notable antioxidant activity (89.36% DPPH scavenging), along with high water-holding capacity (575%), emulsifying activity, and flocculation activity, suggesting its potential as a stabilizing agent in the food industry. Overall, this study provides a comprehensive characterization of Enterococcus hirae MLG3-25-1 EPS, emphasizing its diverse applications in antimicrobial, antioxidant, and food-related industries. These findings lay the groundwork for further exploration and utilization of this EPS in various sectors.

Purification, structural characterization, and bioactive properties of exopolysaccharides from Saccharomyces cerevisiae HD-01

Exopolysaccharides (EPSs), which show excellent biological activities, like anti-tumor, immune regulation, and anti-oxidation activities, have gained widespread attention. In this study, an EPS-producing Saccharomyces cerevisiae HD-01 was identified based on 18S rDNA sequence analysis and an API 20C test. The purified HD-01 EPS was obtained by gel filtration chromatography. High-performance liquid chromatography (HPLC), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR), and nuclear magnetic resonance (NMR) revealed that it was a heteropolysaccharide composed of α-1 (38.3%), α-1, 2 (17.5%), α-1, 6 (14.8%)-linked mannose and α-1, 2, 3, 6 (24.3%), α-1 (3.3%), β-1, 4 (1.8%)-linked glucose. Chemical composition and elemental analysis indicated the existence of sulfation modifications. A scanning electron microscope (SEM) and an atomic force microscope (AFM) revealed that it exhibited a flaky structure with thorn-like protrusions on the three-dimensional surface. X-ray diffraction (XRD) revealed that it was an amorphous non-crystalline substance. HD-01 EPS had great thermostability; probiotic properties; strong antioxidant properties to DPPH, ABTS, and hydroxyl; and good reducing power. The MTT, NO, and neutral red assays demonstrated that it had a great immunomodulatory effect on macrophages RAW264.7. All results suggested that the HD-01 EPS had the potential to be applied in the food and pharmaceutical fields.

Chemical modification of bacterial exopolysaccharides: Antioxidant properties and health potentials

In recent years, there has been a burgeoning interest in the utilization of microbial exopolysaccharides (EPS) because of the added advantage of their renewable, biocompatible, and biodegradable nature in addition to intended applications. The endowed properties of bacterial EPS make them valuable candidates for a wide array of industrial applications. Modification of native EPS is known to enhance various physico-chemical and functional properties. Various modifications such as physical, chemical, biological, and enzymatic modifications were practiced improving the bioactivity of EPS. This paper comprehensively aims to review the most recent chemical modification techniques employed to modify the physico-chemical and functional changes of bacterial EPS in comparison with the unmodified forms. Chemical modification entails strategic alterations to the structure and properties of EPS through various synthetic and semi-synthetic methodologies. Emphasis is given to the antioxidant potential and functional role of these EPS derivatives in human health. Antioxidant properties reveal a significant augmentation in activity compared to their native counterparts. Such enhancement holds a strong promise for potential benefits and therapeutic applications. Chemical derivatives of EPS with overwhelming functional benefits could surely encourage EPS application, particularly as potential hydrocolloids in industrial and biomedical contexts.

A structure-functionality insight into the bioactivity of microbial polysaccharides toward biomedical applications: A review

Microbial polysaccharides (MPs) are biopolymers secreted by microorganisms such as bacteria and fungi during their metabolic processes. Compared to polysaccharides derived from plants and animals, MPs have advantages such as wide sources, high production efficiency, and less susceptibility to natural environmental influences. The most attractive feature of MPs lies in their diverse biological activities, such as antioxidative, anti-tumor, antibacterial, and immunomodulatory activities, which have demonstrated immense potential for applications in functional foods, cosmetics, and biomedicine. These bioactivities are precisely regulated by their sophisticated molecular structure. However, the mechanisms underlying this precise regulation are not yet fully understood and continue to evolve. This article presents a comprehensive review of the most representative species of MPs, including their fermentation and purification processes and their biomedical applications in recent years. In particular, this work presents an in-depth analysis into the structure-activity relationships of MPs across multiple molecular levels. Additionally, this review discusses the challenges and prospects of investigating the structure-activity relationships, providing valuable insights into the broad and high-value utilization of MPs.

Genomic and functional evaluation of exopolysaccharide produced by Liquorilactobacillus mali t6-52: technological implications

BACKGROUND

This study explores the biosynthesis, characteristics, and functional properties of exopolysaccharide produced by the strain Liquorilactobacillus mali T6-52. The strain demonstrated significant EPS production with a non-ropy phenotype.

RESULTS

The genomic analysis unveiled genes associated with EPS biosynthesis, shedding light on the mechanism behind EPS production. These genes suggest a robust EPS production mechanism, providing insights into the strain's adaptability and ecological niche. Chemical composition analysis identified the EPS as a homopolysaccharide primarily composed of glucose, confirming its dextran nature. Furthermore, it demonstrated notable functional properties, including antioxidant activity, fat absorption capacity, and emulsifying activity. Moreover, the EPS displayed promising cryoprotective activities, showing notable performance comparable to standard cryoprotective agents. The EPS concentration also demonstrated significant freeze-drying protective effects, presenting it as a potential alternative cryoprotectant for bacterial storage.

CONCLUSIONS

The functional properties of L. mali T6-52 EPS reveal promising opportunities across various industrial domains. The strain's safety profile, antioxidant prowess, and exceptional cryoprotective and freeze-drying characteristics position it as an asset in food processing and pharmaceuticals.

Mitigating salinity stress through interactions between microalgae and different forms (free-living & alginate gel-encapsulated) of bacteria isolated from estuarine environments

Salinity stress in estuarine environments poses a significant challenge for microalgal survival and proliferation. The interaction between microalgae and bacteria shows promise in alleviating the detrimental impacts of salinity stress on microalgae. Our study investigates this interaction by co-cultivating Chlorella sorokiniana, a freshwater microalga, with a marine growth-promoting bacterium Pseudomonas gessardii, both of which were isolated from estuary. In this study, bacteria were encapsulated using sodium alginate microspheres to establish an isolated co-culture system, preventing direct exposure between microalgae and bacteria. We evaluated microalgal responses to different salinities (5 PSU, 15 PSU) and interaction modes (free-living, gel-encapsulated), focusing on growth, photosynthesis, cellular metabolism, and extracellular polymeric substances (EPS) properties. High salinity inhibited microalgal proliferation, while gel-fixed interaction boosted Chlorella growth rate by 50.7 %. Both attached and free-living bacteria restored Chlorella's NPQ to normal levels under salt stress. Microalgae in the free-living interaction group exhibited a significantly lower respiratory rate compared to the pure algae group (-17.2 %). Increased salinity led to enhanced EPS polysaccharide secretion by microalgae, particularly in interaction groups (19.7 %). Both salt stress and interaction increased the proportion of aromatic proteins in microalgae's EPS, enhancing its stability by modulating EPS glycosidic bond C-O-C and protein vibrations. This alteration caused microalgal cells to aggregate, free-living bacteria co-culture group, and fixed co-culture group increasing by 427.5 %, 567.1 %, and 704.1 %, respectively. In gel-fixed bacteria groups, reduced neutral lipids don't accumulate starch instead, carbon redirects to cellular growth, aiding salt stress mitigation. These synergistic activities between salinity and bacterial interactions are vital in mitigating salinity stress, improving the resilience and growth of microalgae in saline conditions. Our research sheds light on the mechanisms of microalgal-bacterial interactions in coping with salt stress, offering insights into the response of estuarine microorganisms to global environmental changes and their ecological stability.

Advances in microbial exoenzymes bioengineering for improvement of bioplastics degradation

Plastic pollution has become a major global concern, posing numerous challenges for the environment and wildlife. Most conventional ways of plastics degradation are inefficient and cause great damage to ecosystems. The development of biodegradable plastics offers a promising solution for waste management. These plastics are designed to break down under various conditions, opening up new possibilities to mitigate the negative impact of traditional plastics. Microbes, including bacteria and fungi, play a crucial role in the degradation of bioplastics by producing and secreting extracellular enzymes, such as cutinase, lipases, and proteases. However, these microbial enzymes are sensitive to extreme environmental conditions, such as temperature and acidity, affecting their functions and stability. To address these challenges, scientists have employed protein engineering and immobilization techniques to enhance enzyme stability and predict protein structures. Strategies such as improving enzyme and substrate interaction, increasing enzyme thermostability, reinforcing the bonding between the active site of the enzyme and substrate, and refining enzyme activity are being utilized to boost enzyme immobilization and functionality. Recently, bioengineering through gene cloning and expression in potential microorganisms, has revolutionized the biodegradation of bioplastics. This review aimed to discuss the most recent protein engineering strategies for modifying bioplastic-degrading enzymes in terms of stability and functionality, including enzyme thermostability enhancement, reinforcing the substrate binding to the enzyme active site, refining with other enzymes, and improvement of enzyme surface and substrate action. Additionally, discovered bioplastic-degrading exoenzymes by metagenomics techniques were emphasized.

Tapping the biosynthetic potential of marine Bacillus licheniformis LHG166, a prolific sulphated exopolysaccharide producer: structural insights, bio-prospecting its antioxidant, antifungal, antibacterial and anti-biofilm potency as a novel anti-infective lead

The escalating global threat of antimicrobial resistance necessitates prospecting uncharted microbial biodiversity for novel therapeutic leads. This study mines the promising chemical richness of Bacillus licheniformis LHG166, a prolific exopolysaccharide (EPSR2-7.22 g/L). It comprised 5 different monosaccharides with 48.11% uronic acid, 17.40% sulfate groups, and 6.09% N-acetyl glucosamine residues. EPSR2 displayed potent antioxidant activity in DPPH and ABTS+, TAC and FRAP assays. Of all the fungi tested, the yeast Candida albicans displayed the highest susceptibility and antibiofilm inhibition. The fungi Aspergillus niger and Penicillium glabrum showed moderate EPSR2 susceptibility. In contrast, the fungi Mucor circinelloides and Trichoderma harzianum were resistant. Among G+ve tested bacteria, Enterococcus faecalis was the most susceptible, while Salmonella typhi was the most sensitive to G-ve pathogens. Encouragingly, EPSR2 predominantly demonstrated bactericidal effects against both bacterial classes based on MBC/MIC of either 1 or 2 superior Gentamicin. At 75% of MBC, EPSR2 displayed the highest anti-biofilm activity of 88.30% against B. subtilis, while for G-ve antibiofilm inhibition, At 75% of MBC, EPSR2 displayed the highest anti-biofilm activity of 96.63% against Escherichia coli, Even at the lowest dose of 25% MBC, EPSR2 reduced biofilm formation by 84.13% in E. coli, 61.46% in B. subtilis. The microbial metabolite EPSR2 from Bacillus licheniformis LHG166 shows promise as an eco-friendly natural antibiotic alternative for treating infections and oxidative stress.

Revisiting microbial exopolysaccharides: a biocompatible and sustainable polymeric material for multifaceted biomedical applications

Microbial exopolysaccharides (EPS) have gained significant attention as versatile biomolecules with multifarious applications across various sectors. This review explores the valorisation of EPS and its potential impact on diverse sectors, including food, pharmaceuticals, cosmetics, and biotechnology. EPS, secreted by microorganisms, possess unique physicochemical properties, such as high molecular weight, water solubility, and biocompatibility, making them attractive for numerous functional roles. Additionally, EPS exhibit significant bioactivity, contributing to their potential use in pharmaceuticals for drug delivery and tissue engineering applications. Moreover, the eco-friendly and sustainable nature of microbial EPS production aligns with the growing demand for environmentally conscious processes. However, challenges still exist in large-scale production, purification, and regulatory approval for commercial use. Advances in bioprocessing and microbial engineering offer promising solutions to overcome these hurdles. Stringent investigations have concluded EPS as novel sources for sustainable applications that are likely to emerge and develop, further reinforcing the significance of these biopolymers in addressing contemporary societal needs and driving innovation in various industrial sectors. Overall, the microbial EPS represents a thriving field with immense potential for meeting diverse industrial demands and advancing sustainable technologies.

Exopolysaccharides from Enterococcus faecium and Streptococcus thermophilus: Bioactivities, gut microbiome effects, and fermented milk rheology

Exopolysaccharides (EPSs) are carbohydrate polymers that can be produced from probiotic bacteria. This study characterized the EPSs from Enterococcus faecium (EPS-LB13) and Streptococcus thermophilus (EPS-MLB10) and evaluated their biological and technological potential. The EPSs had high molecular weight and different monosaccharide compositions. The EPSs exhibited various biological activities at 250 mg/L, such as scavenging free radicals (10 % to 88.8 %), enhancing antioxidant capacity (714 to 2848 µg/mL), inhibiting pathogens (53 % to 74 %), and suppressing enzymes and cancer cells (2 % to 83 %), etc. The EPSs supported the growth of beneficial gut bacteria from Proteobacteria, Bacteroidetes, Firmicutes, and Acinetobacter in fecal fermentation with total Short-chain fatty acids production from 5548 to 6023 PPM. Moreover, the EPSs reduced the gelation time of fermented skimmed bovine milk by more than half. These results suggest that the EPSs from LB13 and MLB10 have promising applications in the dairy and pharmaceutical industries.

Comparison of Milk Kefirs Obtained from Cow's, Ewe's and Goat's Milk: Antioxidant Role of Microbial-Derived Exopolysaccharides

Different types of milk are used in the production of milk kefir, but little information is available on the release of potentially antioxidant exopolysaccharides (EPS). The aim of this study was to investigate whether the microbial dynamics and EPS release are dependent on the milk substrate. In our study, the inoculated microbial consortium was driven differently by each type of milk (cow, ewe, and goat). This was evident in the sugar consumption, organic acid production, free amino release, and EPS production. The amount and the composition of the secreted EPS varied depending on the milk type, with implications for the structure and functional properties of the EPS. The low EPS yield in ewe's milk was associated with a higher lactic acid production and thus with the use of carbon sources oriented towards energy production. Depending on the milk used as substrate, the EPS showed different monosaccharide and FT-IR profiles, microstructures, and surface morphologies. These differences affected the antiradical properties and reducing power of the EPS. In particular, EPS extracted from cow's milk had a higher antioxidant activity than other milk types, and the antioxidant activity was concentration dependent.

Structural Characterization and Functional Studies of Exopolysaccharide by Native Lacticaseibacillus rhamnosus P14 Isolated from the Moroccan Region

Exopolysaccharides (EPS) are natural polymers synthesized by several microorganisms, including lactic acid bacteria (LAB). They are characterized by a great structural diversity, which gives them interesting biological and pharmacological properties. This work investigates the physicochemical and biological characterization of a new exopolysaccharide (EPS) produced by a wild Lacticaseibacillus rhamnosus P14. The functional groups, chemical bonds, and thermal and morphological properties of the purified EPS-P14 were determined using Fourier Transform Infrared, Nuclear Magnetic Resonance, and X-ray diffraction spectroscopies, as well as Thermo-gravimetric analysis, Differential Scanning Calorimetry and Scanning Electron Microscopy. The functional properties, namely antioxidant and emulsifying activities, were also assessed. The physicochemical analysis revealed that EPS-P14 is a porous and thermally stable polysaccharide with a degradation temperature of 307 °C. NMR and FT-IR studies identified it as a homogeneous α-D-glucan with mainly α-(1 → 6) glycosidic linkage and some α-(1 → 3) branching. EPS-P14 was highly water-soluble and exhibited strong emulsifying and stabilizing properties in a concentration-dependent manner. Furthermore, EPS-P14 demonstrated significant DPPH scavenging and ferric-reducing capacities. These findings suggest that EPS-P14 is a bioactive polysaccharide with potential effects, which could be a promising natural candidate for prospective application.

Coculture of bacterial levans and evaluation of its anti-cancer activity against hepatocellular carcinoma cell lines

This research represents a novel study to assess how coculture affects levan yield, structure, bioactivities, and molecular weight. Among the 16 honey isolates, four bacterial strains recorded the highest levan yield. The Plackett-Burman design showed that the coculture (M) of isolates G2 and K2 had the maximum levan yield (52 g/L) and the effective factors were sucrose, incubation time, and sugarcane bagasse. The CCD showed that the most proper concentrations for maximum levan yield (81 g/L): were 130 g/L of sucrose and 6 g/f of sugarcane bagasse. Levan's backbone was characterized, and the molecular weight was determined. G2 and K2 isolates were identified based on 16 sRNA as Bacillus megaterium strain YM1C10 and Rhizobium sp. G6-1. M levan had promising antioxidant activity (99.66%), slowed the migration activity to a great extent, and recorded 70.70% inhibition against the hepatoblastoma cell line (HepG2) at 1000 µg/mL. Gene expression analysis in liver cancer cell lines (HePG2) revealed that M levan decreased the expression of CCL20), 2GRB2, and CCR6) genes and was superior to Doxo. While increasing the expression of the IL4R and IL-10 genes. The DNA damage values were significantly increased (P < 0.01) in treated liver cancer cell lines with levan M and Doxo. The results referred to the importance of each of the hydroxyl and carboxyl groups and the molecular weight in levans bioactivities.

The antibiofilm potential of a heteropolysaccharide produced and characterized from the isolated marine bacterium Glutamicibacter nicotianae BPM30

Biofilms are the significant causes of 80% of chronic infections in the oral cavity, urinary tract, biliary tube, lungs, gastrointestinal tract, and so on to the general public. Treatment of pathogenic biofilm using bacterial exopolysaccharides (EPS) is an effective and promising strategy. In the present work, a marine bacterium was isolated, studied for exopolysaccharide production, and tested for its antibiofilm activity. Approximately 1.31 ± 0.07 g/L of a purified extracellular polysaccharide was produced and characterized from the isolated marine bacterium Glutamicibacter nicotianae BPM30. The hydrolyzed EPS contains multiple monosaccharides such as rhamnose, fructose, glucose, and galactose. The EPS demonstrated potential antibiofilm activity on four tested pathogens in a concentration-dependent mode. The antibiofilm activity of the purified EPS was studied by crystal violet assay and fluorescence staining method. Comparative inhibition results obtained for the tested strains are 93.25% ± 5.25 and 88.56% ± 2.25 for K. pneumoniae; 92.65% ± 7.6 and 98.33% ± 0.85 for P. aeruginosa; 90.36% ± 6.3 and 52.08% ± 7.74 for S. typhi; 84.62% ± 5.6 and 77.90% ± 5.90 for S. dysenteriae. The results of the present work demonstrated the antibiofilm potential of EPS, which could be helpful in the invention of novel curative approaches in battling bacterial biofilm-related medical complications.

Detoxification of reactive oxygen species by the hyaluronic acid capsule of group A Streptococcus

The pro-inflammatory cytokine IL-6 regulates antimicrobial responses that are broadly crucial in the defense against infection. Our prior work shows that IL-6 promotes the killing of the M4 serotype group A Streptococcus (GAS) but does not impact the globally disseminated M1T1 serotype associated with invasive infections. Using in vitro and in vivo infection models, we show that IL-6 induces phagocyte reactive oxygen species (ROS) that are responsible for the differential susceptibility of M4 and M1T1 GAS to IL-6-mediated defenses. Clinical isolates naturally deficient in capsule, or M1T1 strains deficient in capsule production, are sensitive to this ROS killing. The GAS capsule is made of hyaluronic acid, an antioxidant that detoxifies ROS and can protect acapsular M4 GAS when added exogenously. During in vitro interactions with macrophages and neutrophils, acapsular GAS can also be rescued with the antioxidant N-acetylcysteine, suggesting this is a major virulence contribution of the capsule. In an intradermal infection model with gp91phox -/- (chronic granulomatous disease [CGD]) mice, phagocyte ROS production had a modest effect on bacterial proliferation and the cytokine response but significantly limited the size of the bacterial lesion in the skin. These data suggest that the capsule broadly provides enhanced resistance to phagocyte ROS but is not essential for invasive infection. Since capsule-deficient strains are observed across several GAS serotypes and are competent for transmission and both mild and invasive infections, additional host or microbe factors may contribute to ROS detoxification during GAS infections.

Lactic Acid Bacteria-Derived Exopolysaccharides Mitigate the Oxidative Response via the NRF2-KEAP1 Pathway in PC12 Cells

Parabiotics, including L-EPSs, have been administered to patients with neurodegenerative disorders. However, the antioxidant properties of L-EPSs against H2O2-induced oxidative stress in PC12 cells have not been studied. Herein, we aimed to investigate the antioxidant properties of the L-EPSs, their plausible targets, and their mechanism of action. We first determined the amount of L-EPSs in Lactobacillus delbrueckii ssp. bulgaricus B3 and Lactiplantibacillus plantarum GD2 using spectrophotometry. Afterwards, we studied their effects on TDH, TOS/TAS, antioxidant enzyme activities, and intracellular ROS level. Finally, we used qRT-PCR and ELISA to determine the effects of L-EPSs on the NRF2-KEAP1 pathway. According to our results, the L-EPS groups exhibited significantly higher total thiol activity, native thiol activity, disulfide activity, TAS levels, antioxidant enzyme levels, and gene expression levels (GCLC, HO-1, NRF2, and NQO1) than did the H2O2 group. Additionally, the L-EPS groups caused significant reductions in TOS levels and KEAP1 gene expression levels compared with those in the H2O2 group. Our results indicate that H2O2-induced oxidative stress was modified by L-EPSs. Thus, we revealed that L-EPSs, which regulate H2O2-induced oxidative stress, could have applications in the field of neurochemistry.

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.

Multi-Faceted Bioactivity Assessment of an Exopolysaccharide from Limosilactobacillus fermentum NCDC400: Antioxidant, Antibacterial, and Immunomodulatory Proficiencies

Exopolysaccharides (EPS) are acknowledged for their diverse functional and technological properties. This study presents the characterization of EPS400, an acidic exopolysaccharide sourced from the native probiotic Limosilactobacillus fermentum NCDC400. Notably, this strain has demonstrated previous capabilities in enhancing dairy food texture and displaying in vivo hypocholesterolemic activity. Our investigation aimed to unveil EPS400's potential biological roles, encompassing antioxidant, antibacterial, and immunomodulatory activities. The results underscore EPS400's prowess in scavenging radicals, including the 2,2-diphenyl-1-picrylhydrazyl radical, 2,2'-azino-di-(3-ethylbenzthiazoline sulfonic acid) radical, superoxide radical, hydroxyl radical, and chelating activity targeting the ferrous ion. Furthermore, EPS400 displayed substantial antibacterial effectiveness against prevalent food spoilage bacteria such as Pseudomonas aeruginosa NCDC105 and Micrococcus luteus. Remarkably, EPS400 exhibited the ability to modulate cytokine production, downregulating pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and nitric oxide, while concurrently promoting the release of anti-inflammatory cytokine IL-10 within lipopolysaccharide-activated murine primary macrophages. Additionally, EPS400 significantly (p ≤ 0.05) enhanced the phagocytic potential of macrophages. Collectively, our findings spotlight EPS400 as a promising contender endowed with significant antioxidant, antibacterial, and immunomodulatory attributes. These characteristics propose EPS400 as a potential pharmaceutical or bioactive component, with potential applications in the realm of functional food development.

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.

The structure, characterization and immunomodulatory potential of exopolysaccharide produced by Planococcus rifietoensis AP-5 from deep-sea sediments of the Northwest Pacific

Polysaccharides derived from microorganisms exhibit diverse structures and bioactivities, making them promising candidates for the treatment of various diseases. However, marine-derived polysaccharides and their activities are relatively little known. In this work, fifteen marine strains were isolated from surface sediments in the Northwest Pacific Ocean for screening of EPS production. Planococcus rifietoensis AP-5 produced a maximum yield of EPS at 4.80 g/L. The purified EPS (referred to as PPS) had a molecular weight of 51,062 Da and contained amino, hydroxyl, and carbonyl groups as its major functional groups. PPS primarily consisted of →3)-α-D-Galp-(1 → 4)-α-D-Manp-(1 → 2)-α-D-Manp-(1 → 4)-α-D-Manp-(1 → 4,6)-α-D-Glcp-(1 → 6)-β-D-Galp-(1→, with a branch consisting of T-β-D-Glcp-(1→. Additionally, surface morphology of PPS was hollow, porous, and sphere-like stack. PPS primarily contained C, N, and O elements, with a surface area of 33.76 m2/g, a pore volume of 0.13 cc/g, and a pore diameter of 1.69 nm, respectively. Based on the TG curve, the degradation temperature of PPS was measured to be 247 °C. Furthermore, PPS demonstrated immunomodulatory activity through dose-dependently upregulating the expression level of cytokines. It significantly enhanced the cytokine secretion at a concentration of 5 μg/mL. To sum up, this study offers valuable insights for screening marine polysaccharide-based immunomodulators.

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.

Lactic acid bacteria-derived exopolysaccharide: Formation, immunomodulatory ability, health effects, and structure-function relationship

Exopolysaccharides (EPSs) synthesized by lactic acid bacteria (LAB) have implications for host health and act as food ingredients. Due to the variability of LAB-EPS (lactic acid bacteria-derived exopolysaccharide) gene clusters, especially the glycosyltransferase genes that determine monosaccharide composition, the structure of EPS is very rich. EPSs are synthesized by LAB through the extracellular synthesis pathway and the Wzx/Wzy-dependent pathway. LAB-EPS has a strong immunomodulatory ability. The EPSs produced by different genera of LAB, especially Lactobacillus, Leuconostoc, and Streptococcus, have different immunomodulatory abilities because of their specific structures. LAB-EPS possesses other health effects, including antitumor, antioxidant, intestinal barrier repair, antimicrobial, antiviral, and cholesterol-lowering activities. The bioactivities of LAB-EPS are tightly related to their structures such us monosaccharide composition, glycosidic bonds, and molecular weight (MW). For the excellent physicochemical property, LAB-EPS acts as product improvers in dairy, bakery food, and meat in terms of stability, emulsification, thickening, and gelling. We systematically summarize the detailed process of EPS from synthesis to application, with emphasis on physiological mechanisms of EPS, and specific structure-function relationship, which provides theoretical support for the potential commercial value in the pharmaceutical, chemical, food, and cosmetic industries.

Ultrasonic-assisted enzymatic extraction of sulfated polysaccharide from Skipjack tuna by-products

The effect of ultrasound pretreatment on extraction efficiency of sulfate polysaccharides (SPs) using alcalase from different by-products of Skipjack tuna including head, bone and skin was evaluated. Structural, functional, antioxidant and antibacterial properties of the recovered SPs using the ultrasound-enzyme and enzymatic method were also investigated. Ultrasound pretreatment significantly increased the extraction yield of SPs from all the three by-products compared with the conventional enzymatic method. All extracted SPs showed high antioxidant potential in terms of ABTS, DPPH and ferrous chelating activities where the ultrasound treatment enhanced antioxidant activities of the SPs. The SPs exerted strong inhibiting activity against various Gram-positive and Gram-negative bacteria. The ultrasound treatment remarkably increased antibacterial activity of the SPs against L. monocytogenes but its effect on other bacteria was dependent on the source of the SPs. Altogether, the results suggest that ultrasound pretreatment during enzymatic extraction of SPs from tuna by-products can be a promising approach to improve extraction yield but also bioactivity of the extracted polysaccharides.

Biopharmaceutical applications of microbial polysaccharides as materials: A review

Biological characteristics of natural polymers make microbial polysaccharides an excellent choice for biopharmaceuticals. Due to its easy purifying procedure and high production efficiency, it is capable of resolving the existing application issues associated with some plant and animal polysaccharides. Furthermore, microbial polysaccharides are recognized as prospective substitutes for these polysaccharides based on the search for eco-friendly chemicals. In this review, the microstructure and properties of microbial polysaccharides are utilized to highlight their characteristics and potential medical applications. From the standpoint of pathogenic processes, in-depth explanations are provided on the effects of microbial polysaccharides as active ingredients in the treatment of human diseases, anti-aging, and drug delivery. In addition, the scholarly developments and commercial applications of microbial polysaccharides as medical raw materials are also discussed. The conclusion is that understanding the use of microbial polysaccharides in biopharmaceuticals is essential for the future development of pharmacology and therapeutic medicine.

Shedding Light on the Hidden Benefit of Porphyridium cruentum Culture

Microalgae can represent a reliable source of natural compounds with different activities. Here, we evaluated the antioxidant and anti-inflammatory activity of sulfated exopolysaccharides (s-EPSs) and phycoerythrin (PE), two molecules naturally produced by the red marine microalga Porphyridium cruentum (CCALA415). In vitro and cell-based assays were performed to assess the biological activities of these compounds. The s-EPSs, owing to the presence of sulfate groups, showed biocompatibility on immortalized eukaryotic cell lines and a high antioxidant activity on cell-based systems. PE showed powerful antioxidant activity both in vitro and on cell-based systems, but purification is mandatory for its safe use. Finally, both molecules showed anti-inflammatory activity comparable to that of ibuprofen and helped tissue regeneration. Thus, the isolated molecules from microalgae represent an excellent source of antioxidants to be used in different fields.

Physicochemical and rheological characterizations of a novel exopolysaccharide EPSKar1 and its iron complex EPSKar1-Fe: Towards potential iron-fortification applications

Iron is a micronutrient essential for human health and physiology. Iron-deficiency anemia, the most common form of anemia, may occur from an iron homeostasis imbalance. Iron fortification is a promising and most sustainable and affordable solution to tackle the global prevalence of this anemia. Herein, we investigate physicochemical, rheological and stability characteristics of a novel exopolysaccharide 'EPSKar1' (derived from Lacticaseibacillus rhamnosus strain Kar1) and its iron complex 'EPSKar1-Fe (II)'. Our findings demonstrate that EPSKar1 is a high molecular-weight (7.8 × 10⁵ Da) branched-chain heteropolysaccharide composed of galactose, N-acetylglucosamine, and mannose in a molar ratio of 8:4:1, respectively, and exhibits strong emulsifying and water-holding capacities. We find that EPSKar1 forms strong complexes with Fe, wherein the interactions between EPSKar1-Fe (II) complexes are mediated by sulfate, carboxyl, and hydroxyl groups. The rheological analyses reveal that the EPSKar1 and EPSKar1-Fe (II) complexes exhibited shear thickening and thinning properties in skim milk and water, respectively; however, the suspension of EPSKar1 in skim milk is viscoelastic with predominantly elastic response (G'>G" and tan δ < 1). In comparison, EPSKar1-Fe (II) complex exhibits remarkable stability under various processing conditions, highlighting its usefulness for the development of fortified dairy products. Together, these findings underpin considerable prospects of EPSKar1-Fe (II) complex as a novel iron-fortifier possessing multifarious rheological benefits for food applications.

Effect of Substrate Composition on Yield and Antioxidative Activity of Exopolysaccharides From Lactobacillus fermentum B62

Exopolysaccharides (EPS) can not only give food a unique texture but also has antioxidant capacities. To select the medium composition that influences the yield and antioxidative activity of EPS, Plackett–Burman (PB) design was employed to appraise the effects of carbon sources, nitrogen sources, and inorganic salts on yield and DPPH free radical scavenging (DPPH-FRS) rate of EPS in MRS medium fermented by Lactobacillus fermentum B62. The result indicated that sucrose (p<0.01), peptone (p<0.01), and KH2PO4 (p<0.001) had the most distinguishing comprehensive effects on yield and DPPH-FRS rate of EPS, and fructose also had a noticeable effect on the two factors (p<0.05, p<0.001, respectively). Additionally, glucose (p<0.05), soy protein (p<0.001), yeast extract (p<0.01), KH2PO4 (p<0.001) and Ca(H2PO4)2 (p<0.001) significantly positive affect the yield of EPS. And inulin (p<0.05), tryptone (p<0.001), beef extract powder(p<0.001), NaH2PO4 (p<0.01) and C2H3NaO2 (p<0.05) significantly positive affect the DPPH-FRS rate of EPS. Within the test ranges, sucrose, fructose, peptone and KH2PO4 all showed significant positive relativity to the yield and anti-oxidative activity of EPS.

Effect of fermentation pH on the structure, rheological properties, and antioxidant activities of exopolysaccharides produced by Alteromonas australica QD

The pH value was essential for the growth and metabolism of microorganisms. Acidic pH exopolysaccharide (AC-EPS) and alkaline pH exopolysaccharide (AL-EPS) secreted by A. australica QD mediated by pH were studied in this paper. The total carbohydrate content and molecular weight of AC-EPS (79.59% ± 2.24% (w/w), 8.374 × 10⁵ Da) and AL-EPS (82.48% ± 1.46% (w/w), 6.182 × 10⁵ Da) were estimated and compared. In AC-EPS, mannose (3.78%) and galactose (3.24%) content was more, while the proportion of glucuronic acid was less in comparison to AL-EPS. The scanning electron microscopy revealed the structural differences among the AC-EPS and AL-EPS. Thermogravimetric analysis showed degradation temperatures of 272.8 °C and 244.9 °C for AC-EPS and AL-EPS, respectively. AC-EPS was found to exhibit better rheological properties and emulsifying capabilities, while AL-EPS had superior antioxidant activities. Overall, both AC-EPS and AL-EPS have the potential to be used as emulsifiers and biological antioxidants.

High-Molecular-Weight Dextran-Type Exopolysaccharide Produced by the Novel Apilactobacillus waqarii Improves Metabolic Syndrome: In Vitro and In Vivo Analyses

Metabolic syndrome is a leading medical concern that affects one billion people worldwide. Metabolic syndrome is defined by a clustering of risk factors that predispose an individual to cardiovascular disease, diabetes and stroke. In recent years, the apparent role of the gut microbiota in metabolic syndrome has drawn attention to microbiome-engineered therapeutics. Specifically, lactic acid bacteria (LAB) harbors beneficial metabolic characteristics, including the production of exopolysaccharides and other microbial byproducts. We recently isolated a novel fructophilic lactic acid bacterium (FLAB), Apilactobacillus waqarii strain HBW1, from honeybee gut and found it produces a dextran-type exopolysaccharide (EPS). The objective of this study was to explore the therapeutic potential of the new dextran in relation to metabolic syndrome. Findings revealed the dextran's ability to improve the viability of damaged HT-29 intestinal epithelial cells and exhibit antioxidant properties. In vivo analyses demonstrated reductions in body weight gain and serum cholesterol levels in mice supplemented with the dextran, compared to control (5% and 17.2%, respectively). Additionally, blood glucose levels decreased by 16.26% following dextran supplementation, while increasing by 15.2% in non-treated mice. Overall, this study displays biotherapeutic potential of a novel EPS to improve metabolic syndrome and its individual components, warranting further investigation.

Lacticaseibacillus rhamnosus-Derived Exopolysaccharide Attenuates D-Galactose-Induced Oxidative Stress and Inflammatory Brain Injury and Modulates Gut Microbiota in a Mouse Model

This study aimed to investigate the protective effect of a novel exopolysaccharide EPSRam12, produced by Lacticaseibacillus rhamnosus Ram12, against D-galactose-induced brain injury and gut microbiota dysbiosis in mice. The findings demonstrate that EPSRam12 increases the level of antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase, total antioxidant capacity, and the level of anti-inflammatory cytokine IL-10, while decreasing malonaldehyde, nitric oxide, pro-inflammatory cytokines including TNF-α, IL-1β, IL-6, MCP-1, and the mRNA expression of cyclooxygenase-2, inducible nitric oxide synthase, and the activation of nuclear factor-kappa-B in the brain tissues of D-galactose-treated mice. Further analyses reveal that EPSRam12 improves gut mucosal barrier function and increases the levels of short-chain fatty acids (SCFAs) in the intestine while restoring gut microbial diversity by enriching the abundance of SCFA-producing microbial genera Prevotella, Clostridium, Intestinimonas, and Acetatifactor while decreasing potential pathobionts including Helicobacter. These findings of antioxidative and anti-inflammatory effects in the brain and ameliorative effects on epithelial integrity, SCFAs and microbiota in the gut, provide novel insights into the effect of EPSRam12 intervention on the gut–microbiome–brain axis and should facilitate prospective understanding of microbial exopolysaccharide for improved host health.

Structural characterization and biological activities of polysaccharide iron complex synthesized by plant polysaccharides: A review

Iron deficiency anemia can lead to a variety of functional disorders, which is one of the highest incidence of nutrient deficiency diseases. The direct addition of iron to food will not only brings difficulties to the production of products, but also brings damages to human body. In recent years, international studies have shown that polysaccharide iron complex (PIC) not only has a variety of pharmacological activities of polysaccharide itself, but also has the function of supplementing iron, so it is a good iron supplement. With the advantages of good solubility, high iron content, low gastrointestinal irritation and high bioavailability, PIC is an effective iron supplement for iron deficiency anemia and has attracted more and more attention. In this paper, the different preparation methods, structural characterization, biological activities and clinical applications of PIC synthesized by natural polysaccharides from plant were reviewed, in order to provide theoretical basis for the development and application of PIC.

Molecular Characterization and Biocompatibility of Exopolysaccharide Produced by Moderately Halophilic Bacterium Virgibacillus dokdonensis from the Saltern of Kumta Coast

The use of natural polysaccharides as biomaterials is gaining importance in tissue engineering due to their inherent biocompatibility. In this direction, the present study aims to explore the structure and biocompatibility of the EPS produced by Virgibacillus dokdonensis VITP14. This marine bacterium produces 17.3 g/L of EPS at 96 h of fermentation. The EPS was purified using ion exchange and gel permeation chromatographic methods. The porous web-like structure and elemental composition (C, O, Na, Mg, P, S) of the EPS were inferred from SEM and EDX analysis. AFM analysis revealed spike-like lumps with a surface roughness of 84.85 nm. The zeta potential value of −10 mV indicates the anionic nature of the EPS. Initial molecular characterization showed that the EPS is a heteropolysaccharide composed of glucose (25.8%), ribose (18.6%), fructose (31.5%), and xylose (24%), which are the monosaccharide units in the HPLC analysis. The FTIR spectrum indicates the presence of functional groups/bonds typical of EPSs (O-H, C-H, C-O-H, C-O, S=O, and P=O). The polymer has an average molecular weight of 555 kDa. Further, NMR analysis revealed the monomer composition, the existence of two α- and six β-glycosidic linkages, and the branched repeating unit as → 1)[α-D-Xylp-(1 → 2)-α-D-Glcp-(1 → 6)-β-D-Glcp-(1 → 5)]-β-D-Frup-(2 → 2)[β-D-Xylp-(1 → 4)]-β-D-Xylp-(1 → 6)-β-D-Fruf-(2 → 4)-β-D-Ribp-(1 →. The EPS is thermally stable till 251.4 °C. X-ray diffraction analysis confirmed the semicrystalline (54.2%) nature of the EPS. Further, the EPS exhibits significant water solubility (76.5%), water-holding capacity (266.8%), emulsifying index (66.8%), hemocompatibility (erythrocyte protection > 87%), and cytocompatibility (cell viability > 80% on RAW264.7 and keratinocyte HaCaT cells) at higher concentrations and prolongs coagulation time in APTT and PT tests. Our research unveils the significant biocompatibility of VITP14 EPS for synthesizing a variety of biomaterials.