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

Proteomics and metabolomics elucidate the biosynthetic pathway of acid stress-induced exopolysaccharides and its impact on growth phenotypes in Lactiplantibacillus plantarum HMX2

Lactiplantibacillus plantarum has been well acknowledged to produce exopolysaccharides (EPS) as a defense mechanism against acid stress. However, the complete biosynthetic pathway of EPS in L. plantarum and its impact on the cell growth and primary metabolism were still unclear. To fill these gaps, we carried out phenotypic, proteomic and metabolomics analysis of L. plantarum HMX2 cultured under different acidic conditions. Component and structure analysis showed that the repeating unit of EPS consisted of N-acetylmannosamine, N-acetylglucosamine, galactose, mannoses and glucoses. Multiomics analysis facilitated the curation and entablement of the complete EPS biosynthetic pathway ready for use in genome-scale metabolic models. Furthermore, proteomics and metabolomics data indicated that compared to the pH 6.5 condition, the acid stress at pH 4.5 significantly accelerated glycolysis and EPS biosynthesis processes while reduced the metabolic fluxes through the TCA cycle and the lactic acid fermentation, which suggested a trade-off between primary and secondary metabolism.

Advances in research on the intestinal microbiota in the mechanism and prevention of colorectal cancer (Review)

The intestinal microbiota represents a diverse population that serves a key role in colorectal cancer (CRC) and its treatment outcomes. Advancements in sequencing have revealed notable shifts in microbial composition and diversity among individuals with CRC. Concurrently, animal models have elucidated the involvement of specific microbes such as Lactobacillus fragilis, Escherichia coli and Fusobacterium nucleatum in the progression of CRC. The present review aimed to highlight contributions of intestinal microbiota to the pathogenesis of CRC, the effects of traditional treatments on intestinal microbiota and the potential for microbiota modulation as a therapeutic strategy for CRC.

LytR Family Transcriptional Regulator EpsA Positively Regulates Exopolysaccharide Biosynthesis in Lacticaseibacillus casei

Exopolysaccharides (EPSs) produced by Lacticaseibacillus casei have great potential for application in the food industry. However, the transcriptional regulation of EPS biosynthesis in L. casei remains unclear. Here, the transcription profile of the eps gene cluster was characterized in L. casei. Co-transcriptional analysis suggested that EPSs harbor three operons controlled by promoters P2169-2170, P2185-2186, and P2189-2190, respectively. Electrophoretic mobility shift assay showed that EpsA, the sole transcriptional regulator in the eps gene cluster, directly binds promoters P2169-2170 and P2189-2190. Overexpression of epsA increased the EPS titer (243.60 mg/L) with significantly enhanced expression of three eps genes, suggesting EpsA as a transcriptional activator for EPS biosynthesis. Furthermore, RNA-seq analysis revealed that 67 genes were significantly changed with the epsA knockout, especially 16 genes associated with EPS biosynthesis. This indicated that EpsA may be a global/pleiotropic regulator. Collectively, our findings lay the foundation for elucidating the transcriptional regulation of EPS biosynthesis in L. casei.

Swine Gut Lactic Acid Bacteria and Their Exopolysaccharides Differentially Modulate Toll-like Receptor Signaling Depending on the Agave Fructans Used as a Carbon Source

Exopolysaccharides (EPSs) produced by probiotic bacteria have garnered attention due to their effects on the gut health of humans and animals. The nutrients that probiotics access during their growth are essential for producing beneficial effects on host health. Direct immunomodulatory effects of graminan-type fructans (GTFs) from Agave tequilana through toll-like receptors (TLRs) have been demonstrated. However, the immunomodulatory effects of these fructans, mediated through the EPSs produced by the probiotics cultivated with them, remain unexplored. We explored the immunomodulatory effects of lactic acid bacteria (LAB) strains isolated from swine and their EPSs, based on the GTFs used as carbon sources during their growth. While the LAB strains activated the NF-κB pathway independently of the GTF source, their EPSs activated it in a GTF source-dependent manner. LAB activation through TLR2 showed a GTF source dependency, whereas their EPSs activated TLR2 independently of the GTF source. The LAB and their EPSs activated TLR4 in a GTF source-dependent manner. Both the LAB and their EPSs inhibited the activation of TLR2 and TLR4 agonists, which exhibited a strong dependence on the GTF source. The strength of GTF C's immunomodulatory effects on LAB illustrates its specificity, its impact on the EPS structure, and its biological effects. Our results support the promising health benefits of this synbiotic model for swine health and lowering inflammation.

Exopolysaccharide from Bifidobacterium longum subsp. infantis E4: Structural analysis and immunoregulation activities

Exopolysaccharides (EPS) have the effects of anti-inflammatory, antimicrobial and immunomodulatory. This study described the structural characteristics of EPS-1 and EPS-2 and investigated their modulatory effects on immunity by cyclophosphamide (CTX)-induced immunocompromised mice. EPS-1 primarily consisted of glucose and mannose. EPS-2 was mostly comprised of galactose, glucose and mannose. Fourier-transform infrared (FT-IR) analysis revealed that EPS-1 and EPS-2 exhibited absorption peaks including CH and CO groups. Congo red test indicated that both of them had triple-helical conformations. Methylation and nuclear magnetic resonance (NMR) analyzed the main chain of EPS-1 comprising →4,6)-α-D-Glcp-(1→,→4)-α-D-Glcp-(1→,→4,6)-α-D-Glcp-(1→,2)-α-D-Manp-(1→,→6)-α-D-Manp-(1→. The main chain of EPS-2 was composed of α-D-Manp-(1→,→4)-α-D-Galp-(1→,→2,6)-α-D-Glcp-(1→,→2)-α-D-Manp-(1→,3)-α-D-Glcp-(1→. Additionally, EPS-1 and EPS-2 alleviated decreases in spleen and thymus index in mice subjected to CTX induction. Compared with the Model control (MC) group, the Splenic lymphocyte proliferations and NK cell activity in EPS-1 and EPS-2 groups were increased. Th1, Th2, Th17 and Treg cells in EPS-1 group were increased to 5.50 %, 0.36 %, 2.87 %, 3.53 %, respectively, and 5.39 %, 0.33 %, 2.40 %, 3.33 % in EPS-2 group. The levels of serum inflammatory cytokines (such as IFN-γ, IL-1β, IL-2, IL-6, IL-10 and TNF-α) were also increased in EPS-1 and EPS-2 groups to varying degree compare with the MC group. Therefore, the results unveiled that EPS has the potential to regulate the body immunity function.

Identification and evaluation of active fractions from Radix Hedysari polysaccharides: Their regulatory impacts on intestinal flora and metabolism in mice

Polysaccharides are one of the primary active components of Radix Hedysari, although their regulatory effects on gut microbiota remain poorly understood. In this study, Radix Hedysari polysaccharides (RHPS) were isolated and purified, yielding three fractions: RHPS-1, RHPS-2, and RHPS-4. The yields of these fractions were 51.33 %, 3.15 %, and 2.34 %, respectively, with weight-average molecular weights of 18.781, 25.660, and 100.149 kDa. The three polysaccharides were composed of arabinose, galactose, glucose, glucuronic acid. RHPS-1 exhibits good antioxidant, antibacterial, and immune-enhancing activities. Further purification of RHPS-1 yielded RHPS-1-1, and it was found that RHPS-1-1 enhances the growth of beneficial bacteria while suppressing the growth of harmful bacteria in mice. Additionally, mice treated with RHPS-1-1 were primarily involved in bile acid, short-chain fatty acid, and energy metabolism pathways. Our results represent the first demonstration that RHPS-1-1 exhibits good biological activity and possesses the ability to regulate the gut microbiota and its metabolites in mice.

Current state, challenges and future orientations of the applications of lactic acid bacteria exopolysaccharide in foods

In the quest for a balanced diet and better health, the global shift towards nutrient-dense foods highlights the multiple roles of lactic acid bacteria exopolysaccharides (LAB-EPS) in improving food quality and health. This paper offers a comprehensive survey of LAB-EPS, focusing on their classification, biosynthesis pathways and application in the food industry, from dairy products to bakery products and meat. It highlights the impact of LAB-EPS on the texture and sensory qualities of food. Despite their promising prospects, these polysaccharides face various application challenges in the food industry. These include variability in EPS production among LAB strains, complexity in structure-function relationships, and limited understanding of their health benefits. In order to address these issues, the review identifies and suggests future research directions to optimize the production of LAB-EPS, elucidating their health benefit mechanisms, and expanding their application scope. In summary, this review aims to contribute to advance innovation and progress in the food industry by developing healthier food options and deepening the understanding of LAB-EPS in promoting human health.

Isolation, structural characterization and multiple activity of a novel exopolysaccharide produced by Gelidibacter sp. PG-2

Microbial exopolysaccharides have been extensively explored due to their distinctive structural features and physiological activities, making them suitable for diverse applications in the food and environmental applications. Current studies mainly focus on the structural and functional characterization of exopolysaccharides from known strains, with limited exploration of novel strains. In this study, a novel exopolysaccharide was produced by Gelidibacter sp. PG-2 with a yield of 874 mg·L-1. The purified exopolysaccharides, termed as ZPS, had a molecular weight of 45,514 Da and contained numerous hydroxyl and carbonyl groups. ZPS was a heteropolysaccharide composed of mannose, glucosamine, glucuronic acid, galactonic acid, galactosamine, glucose, galactose, and fucose, with a molar ratio of 54.98: 4.05: 6.69: 1.00: 1.46: 2.95: 2.92: 1.55. ZPS linkage comprised Glcp-(1→, Manp-(1→, →2)-Manp-(1→, →4)-Galp-(1→, and →4)-Manp-(1→. The morphology of ZPS presented the smooth surface, spherical nanoparticle, and irregular network structure. ZPS demonstrated thermal stability and emulsification activity. ZPS potently stimulated macrophage phagocytic function and effectively inhibited the migration of cancer cells, thereby enhancing overall immunomodulatory activity. Additionally, ZPS featured cryoprotective activity and flocculation property. Overall, the multiple activity of ZPS hold tremendous potential in the food and pharmaceutical industries, offering new dimensions for novel microbial exopolysaccharides.

In Vitro Cholesterol-Lowering Bioactivity, Synthetic Pathway, and Structural Characterization of Exopolysaccharide Synthesized by Schleiferilactobacillus harbinensis Z171

A strain identified as Schleiferilactobacillus harbinensis was isolated from Chinese sauerkraut, and its exopolysaccharide (EPS) exhibited excellent in vitro cholesterol-lowering bioactivity. Besides, the whole genome of this strain and the structure characteristics of the purified EPS were investigated in this study. S. harbinensis Z171 presented a strong EPS production capacity, with five nucleotide sugar biosynthesis pathways regulated by an EPS synthesis gene cluster. Structural characterization revealed that the purified fraction F-EPS1A was a neutral polysaccharide with a molecular weight of 6.4 × 104 Da. The structure of F-EPS1A contained a backbone that comprised blocks of four 1,2-linked and three 1,3-linked alpha mannose units. Some 1,2-linked alpha mannose residues were branched at C6 with side chains formed by single alpha mannose or a disaccharide consisting of 1,6-linked alpha mannose residues. The structural characteristics endowed F-EPS1A with a high level of cholesterol-lowering bioactivity. In addition, whole genome analysis indicated that S. harbinensis Z171 possessed a strong EPS production capacity. These findings suggested that the EPS produced by S. harbinensis Z171 could be applied as a potential cholesterol-lowering prebiotic agent or supplement in functional food.

Harnessing the polysaccharide production potential to optimize and expand the application of probiotics

Certain probiotic microorganisms can synthesize important bioproducts, including polysaccharides as components of cellular structure or extracellular matrix. Probiotic-derived polysaccharides have been widely applied in food, pharmaceutical, and medical fields due to their excellent properties and biological activities. The development of polysaccharide production potential has become a driving force for facilitating biotechnological applications of probiotics. Based on technical advances in synthetic biology, significant progress has recently been made in engineering probiotics with efficient biosynthesis of polysaccharides. Herein, this review summarizes probiotics chassis and genetic tools used for polysaccharide production. Then, probiotic polysaccharides and relevant biosynthesis mechanisms are also clearly described. Next, we introduce strategies for preparing high-yield, controllable molecular weight or non-native polysaccharides by adjusting metabolic pathways and integrating expression elements in probiotics. Finally, some prospective and well-established contributions of exogenous and in situ polysaccharides in probiotics' stability, bioactivity, and therapeutic effects are presented. Our viewpoints on advancing the efficient biomanufacturing of valuable biopolymers in probiotics and engineering probiotics with customized features are provided to exploit probiotics' industrial and biomedical applications.

Water-soluble polysaccharides from Torreya grandis nuts: Structural characterization and anti-inflammatory activity

Torreya grandis (T. grandis) nuts are widely consumed as a functional food in China. In this study, we investigated the structural characteristics of T. grandis nuts polysaccharides and evaluated their potential biological functions with anti-inflammatory activities. Polysaccharides (TGP) were extracted from T. grandis nuts using water extraction and alcohol precipitation methods. Through a series of purification steps, three heteropolysaccharides (TGP-0a, TGP-2a, and TGP-3a) with distinct molecular weights, monosaccharide compositions, and surface morphologies were isolated. Their anti-inflammatory activities were screened, and TGP-0a was shown to be the most effective component. By combining NMR and methylation studies, TGP-0a was predominantly composed of linear α-1,4-glucan region and linear β-1,4-(gluco)mannan region. In cellular anti-inflammatory assays, TGP-0a significantly diminished the release of pro-inflammatory cytokines. Furthermore, by lowering the levels of iNOS and COX-2, TGP-0a decreased the release of inflammatory mediators (NO and ROS), thereby reducing oxidative stress and inflammatory response. In conclusion, T. grandis nut polysaccharides, particularly TGP-0a, show strong potential as natural anti-inflammatory agents for functional foods and pharmaceutical applications.

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.

Environmental Changes Driving Shifts in the Structure and Functional Properties of the Symbiotic Microbiota of Daphnia

Symbiotic microbiota significantly influence the development, physiology, and behavior of their hosts, and therefore, they are widely studied. However, very few studies have investigated the changes in symbiotic microbiota across generations. Daphnia magna originating from the Qinghai-Tibetan Plateau were cultured through seven generations in our laboratory, and the symbiotic microbiota of D. magna were sequenced using a 16S rRNA amplicon to analyze changes in the structure and functional properties of the symbiotic microbiota of D. magna from a harsh environment to an ideal environment. We detected substantial changes in the symbiotic microbiota of D. magna across generations. For example, the genus Nevskia, a member of the gamma-subclass Proteobacteria, had the highest abundance in the first generation (G1), followed by a decrease in abundance in the fourth (G4) and seventh (G7) generations. The gene functions of the microbiota in different generations of D. magna also changed significantly. The fourth generation was mainly rich in fatty acyl-CoA synthase, acetyl-CoA acyltransferase, phosphoglycerol phosphatase, etc. The seventh generation was mainly rich in osmotic enzyme protein and ATP-binding protein of the ABC transport system. This study confirms that the alterations in the structure and functional properties of the symbiotic microbiota of D. magna under changing environments are typical responses of D. magna to environmental changes.

Methods for Detection, Extraction, Purification, and Characterization of Exopolysaccharides of Lactic Acid Bacteria-A Systematic Review

Exopolysaccharides (EPSs) are large-molecular-weight, complex carbohydrate molecules and extracellularly secreted bio-polymers released by many microorganisms, including lactic acid bacteria (LAB). LAB are well known for their ability to produce a wide range of EPSs, which has received major attention. LAB-EPSs have the potential to improve health, and their applications are in the food and pharmaceutical industries. Several methods have been developed and optimized in recent years for producing, extracting, purifying, and characterizing LAB-produced EPSs. The simplest method of evaluating the production of EPSs is to observe morphological features, such as ropy and mucoid appearances of colonies. Ethanol precipitation is widely used to extract the EPSs from the cell-free supernatant and is generally purified using dialysis. The most commonly used method to quantify the carbohydrate content is phenol-sulfuric acid. The structural characteristics of EPSs are identified via Fourier transform infrared, nuclear magnetic resonance, and X-ray diffraction spectroscopy. The molecular weight and composition of monosaccharides are determined through size-exclusion chromatography, thin-layer chromatography, gas chromatography, and high-performance liquid chromatography. The surface morphology of EPSs is observed via scanning electron microscopy and atomic force microscopy, whereas thermal characteristics are determined through thermogravimetry analysis, derivative thermogravimetry, and differential scanning calorimetry. In the present review, we discuss the different existing methods used for the detailed study of LAB-produced EPSs, which provide a comprehensive guide on LAB-EPS preparation, critically evaluating methods, addressing knowledge gaps and key challenges, and offering solutions to enhance reproducibility, scalability, and support for both research and industrial applications.

Antioxidant potential of exopolysaccharides from lactic acid bacteria: A comprehensive review

Exopolysaccharides (EPSs) from lactic acid bacteria (LAB) have multifunctional capabilities owing to their diverse structural conformations, monosaccharide compositions, functional groups, and molecular weights. A review paper on EPS production and antioxidant potential of different LAB genera has not been thoroughly reviewed. Therefore, the current review provides comprehensive information on the biosynthesis of EPSs, including the isolation source, type, characterization techniques, and application, with a primary focus on their antioxidant potential. According to this review, 17 species of Lactobacillus, five species of Bifidobacterium, four species of Leuconostoc, three species of Weissella, Enterococcus, and Lactococcus, two species of Pediococcus, and one Streptococcus species have been documented to exhibit antioxidant activity. Of the 111 studies comprehensively reviewed, 98 evaluated the radical scavenging activity of EPSs through chemical-based assays, whereas the remaining studies documented the antioxidant activity using cell and animal models. Studies have shown that different LAB genera have a unique capacity to produce homo- (HoPs) and heteropolysaccharides (HePs), with varied carbohydrate compositions, linkages, and molecular weights. Leuconostoc, Weissella, and Pediococcus were the main HoPs producers, whereas the remaining genera were the main HePs producers. Recent trends in EPSs production and blending to improve their properties have also been discussed.

Beneficial effects of duck-derived lactic acid bacteria on growth performance and meat quality through modulation of gut histomorphology and intestinal microflora in Muscovy ducks

Duck-derived lactic acid bacteria (DDL) are a crucial beneficial bacterium in the intestines, contributing significantly to the health of ducks. However, the mechanism by which these DDL improves the growth performance and meat quality of Muscovy duck is not clear. In this study, A total of 800 male Muscovy ducks, initially weighing 50.15 ± 5.37 g, were randomly allocated into 4 groups, each with 4 replicates, consisting of 50 ducks per replicate. The control group consumed deep well water, while the experimental groups were given water supplemented with 1%, 3%, and 5% DDL (1.59×108 CFU/mL). The study duration was 70 d. The results revealed that Muscovy ducks drinks with the DDL significant reduced the feed conversion ratio (FCR) (P < 0.05) and increased the sweetness and richness of duck meat, among which the 5% drinking group has the most significant difference. Further study finding, the DDL significantly increased the height of villi, the ratio of villi height/crypt depth (V/C) on jejunum and colon, and the ratio of acidic mucus, neutral mucus, and glycogen to tissue area in both the duodenum and ileum of Muscovy ducks, and significantly decreased the tunel positive cells. Moreover, DDL significantly enhanced the abundance of genus beneficial bacterium (Bacillus, lentilactobacillus, Bacterodies, Lactobacillus) on duodenum and ileum. Additionally, drink with the DDL elevated the level of IgG in blood and the immune indices of the thymus and the fabricius bursa (P<0.05). Meanwhile, the meat composition analysis demonstrated that Muscovy duck drinks with the DDL raised the level of the saturated fatty acid rate(C12:0), and polyunsaturated fatty acid (C18:2 n-6 and C20:5 n-3,), and the monounsaturated (C18:1 n-7, and C18:1 n-9). Furthermore, correlation analysis finding that the growth performance of Muscovy ducks was positively correlated with the height of villi, the ratio of villi height/crypt depth (V/C), the abundance of genus beneficial bacterium. And the meat quality of Muscovy ducks has positively correlated with genus beneficial bacterium in intestinal, glutamic acid, saturated fatty acid rate and polyunsaturated fatty acid. This finding suggest DDL is an effective strategy to improve the growth performance and meat quality of Muscovy ducks by gut histomorphology and intestinal microflora.

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.

Structural characteristics, immune-activating mechanisms in vitro, and immunomodulatory effects in vivo of the exopolysaccharide EPS53 from Streptococcus thermophilus XJ53

Our previous investigations have successfully identified the repeating structural units of EPS53, an exopolysaccharide derived from Streptococcus thermophilus XJ53 fermented milk, and substantiated its potential immunomodulatory properties. The present study further elucidated the structural characteristics of EPS53 and investigated the underlying mechanisms governing its in vitro immunoreactivity as well as its in vivo immunoreactivity. The results obtained from multi-detector high performance gel filtration chromatography revealed that EPS53 adopted a rigid rod conformation in aqueous solution, with the weight-average molecular weight of 1464 kDa, the number-average molecular weight of 694 kDa, and the polydispersity index of 2.11. Congo red experiment confirmed the absence of a triple helix conformation. Scanning electron microscopy showed that EPS53 displayed a three-dimensional fibrous structure covered with flakes. The in vitro findings indicated that EPS53 enhanced phagocytosis ability, reactive oxygen species (ROS) production, and cytokine levels of macrophages via the TLR4-mediated NF-κB/MAPK signaling pathways as confirmed by immunofluorescence staining experiments, inhibition blocking experiments, and Western blot assay. Additionally, the in vivo experiments demonstrated that EPS53 significantly increased macrophage and neutrophil number while enhancing NO and ROS levels in zebrafish larvae; thus, providing further evidence for the immunomodulatory efficacy of EPS53.

Comparative genome analysis of microbial strains marketed for probiotic interventions: an extension of the Integrated Probiotic Database

Background: Members of the Bifidobacterium genus and lactobacilli are the most commonly used probiotics to promote human health. In this context, genome-based in silico analyses have been demonstrated as a fast and reliable tool for identifying and characterizing health-promoting activities imputed to probiotics. Methods: This study is an extension of the Integrated Probiotic Database (IPDB) previously created on probiotics of the genus Bifidobacterium, facilitating a comprehensive understanding of the genetic characteristics that contribute to the diverse spectrum of beneficial effects of probiotics. The strains integrated into this new version of the IPDB, such as various lactobacilli and strains belonging to the species Streptococcus thermophilus (S. thermophilus) and Heyndrickxia coagulans (H. coagulans) (formerly Bacillus coagulans), were selected based on the labels of probiotic formulations currently on the market and using the bacterial strains whose genome had already been sequenced. On these bacterial strains, comparative genome analyses were performed, mainly focusing on genetic factors that confer structural, functional, and chemical characteristics predicted to be involved in microbe-host and microbe-microbe interactions. Results: Our investigations revealed marked inter- and intra-species variations in the genetic makeup associated with the biosynthesis of external structures and bioactive metabolites putatively associated with microbe- and host-microbe interactions. Conclusion: Although genetic differences need to be confirmed as functional or phenotypic differences before any probiotic intervention, we believe that considering these divergences will aid in improving effective and personalized probiotic-based interventions.

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.

Structural Characterization and Biological Properties Analysis of Exopolysaccharides Produced by Weisella cibaria HDL-4

An exopolysaccharide (EPS)-producing strain, identified as Weissella cibaria HDL-4, was isolated from litchi. After separation and purification, the structure and properties of HDL-4 EPS were characterized. The molecular weight of HDL-4 EPS was determined to be 1.9 × 10⁶ Da, with glucose as its monosaccharide component. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) analyses indicated that HDL-4 EPS was a D-glucan with α-(1→6) and α-(1→4) glycosidic bonds. X-ray diffraction (XRD) analysis revealed that HDL-4 EPS was amorphous. Scanning electron microscope (SEM) and atomic force microscope (AFM) observations showed that HDL-4 EPS possesses pores, irregular protrusions, and a smooth layered structure. Additionally, HDL-4 EPS demonstrated significant thermal stability, remaining stable below 288 °C. It exhibited a strong metal ion adsorption activity, emulsification activity, antioxidant activity, and water-retaining property. Therefore, HDL-4 EPS can be extensively utilized in the food and pharmaceutical industries as an additive and prebiotic.

Structural characterization of extracellular polysaccharides from Phellinus igniarius SH-1 and their therapeutic effects on DSS induced colitis in mice

Phellinus igniarius is a valuable medicinal and edible mushroom, and its polysaccharides exhibit excellent anti-inflammatory activity. During liquid fermentation to produce P. igniarius mycelia, the fermentation liquid is often discarded, but it contains extracellular polysaccharides. To better utilize these resources, P. igniarius SH-1 was fermented in a 100 L fermenter, and PIPS-2 was isolated and purified from the fermentation broth. The structural characteristics and anti-inflammatory activity of PIPS-2 were determined. PIPS-2 had a molecular weight of 22.855 kDa and was composed of galactose and mannose in a molar ratio of 0.38:0.62. Structural analysis revealed that the main chain of PIPS-2 involved →2)-α-D-Manp-(1 → 3)-β-D-Galf-(1→, and the side chains involved α-D-Manp-(1 → 6)-α-D-Manp-(1→, α-D-Manp-(1 → 3)-α-D-Manp-(1→, and α-D-Manp-(1. PIPS-2 alleviated the symptoms of dextran sodium sulfate (DSS)-induced colitis in mice, improved the imbalance of inflammatory factors and antioxidant enzymes, and increased short-chain fatty acid contents. Combining the intestinal flora and metabolite results, PIPS-2 was found to regulate the abundance of Firmicutes, Lachnospiraceae_NK4A136_group, Proteobacteria, Bacteroides, and many serum metabolites including hexadecenal, copalic acid, 8-hydroxyeicosatetraenoic acid, artepillin C, and uric acid, thereby ameliorating metabolite related disorders in mice with colitis. In summary, PIPS-2 may improve colitis in mice by regulating the gut microbiota and metabolites.

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.

Fault diagnosis based on counterfactual inference for the batch fermentation process

Fault diagnosis plays a pivotal role in identifying the root causes of a fault. Current fault diagnosis methods encounter the shortcomings being unable to assess the fault amplitude or having low efficiency for batch fermentation process. In order to solve the above problems, this paper proposes a fault detection model named convolutional neural network based on variational autoencoder (CNN-VAE) and a fault diagnosis based on counterfactual inference (FDCI). To begin with, quality-related process variables are selected using mutual information (MI). Next, a two-dimensional moving window is used to obtain input sequences from the process data. Then, two statistics from the latent and residual domains of the CNN-VAE model are constructed for fault detection. Additionally, once a fault occurs, FDCI is used to locate the root cause of a fault. Finally, a simulation process and a real-world L. plantarum batch fermentation process are provided to demonstrate the effectiveness of the proposed approache.

Reuterin, Phenyllactic Acid, and Exopolysaccharides as Main Antifungal Molecules Produced by Lactic Acid Bacteria: A Scoping Review

The primary goal of this scoping review is to collect, analyze, and critically describe information regarding the role of the main compounds (reuterin, phenyllactic acid, and exopolysaccharides) produced by LAB that possess antifungal properties and provide some suggestions for further research. The use of lactic acid bacteria (LAB) to mitigate spoilage and extend the shelf life of foodstuffs has a long history. Recently, there has been a growing interest in the unique properties of these additions to the foodstuffs in which they are applied. In recent studies regarding biopreservation, significant attention has been given to the role of these microorganisms and their metabolites. This fascinating recent discipline aims not only to replace traditional preservation systems, but also to improve the overall quality of the final product. The biologically active by-products produced by lactic acid bacteria are synthesized under certain conditions (time, temperature, aerobiosis, acidity, water activity, etc.), which can be enacted through one of the oldest approaches to food processing: fermentation (commonly used in the dairy and bakery sectors). This study also delves into the biosynthetic pathways through which they are synthesized, with a particular emphasis on what is known about the mechanisms of action against molds in relation to the type of food.

A dual catalytic functionalized hollow mesoporous silica-based nanocarrier coated with bacteria-derived exopolysaccharides for targeted delivery of irinotecan to colorectal cancer cells

In this study, we introduced a multifunctional hollow mesoporous silica-based nanocarrier (HMSN) for the targeted delivery of irinotecan (IRT) to colorectal cancer cells. Due to their large reservoirs, hollow mesoporous silica nanoparticles are suitable platforms for loading significant amounts of drugs for sustained drug release. To respond to pH and redox, HMSNs were functionalized with cerium and iron oxides. Additionally, they were coated with bacterial-derived exopolysaccharide (EPS) as a biocompatible polymer. In vitro analyses revealed that cytotoxicity induced in cancer cells through oxidative stress, mediated by mature nanocarriers (EPS.IRT.Ce/Fe.HMSN), was surprisingly greater than that caused by free drugs. Cerium and iron ions, in synergy with the drug, were found to generate reactive oxygen species when targeting the acidic pH within lysosomes and the tumor microenvironment. This, in turn, triggered cascade reactions, leading to cell death. In vivo experiments revealed that the proposed nanocarriers had no noticeable effect on healthy tissues. These findings indicate the selective delivery of the drug to cancerous tissue and the induction of antioxidant effects due to the dual catalytic properties of cerium in normal cells. Accordingly, this hybrid drug delivery system provides a more effective treatment for colorectal cancer with the potential for cost-effective scaling up.

Structural characteristics and functional properties of a fucose containing prebiotic exopolysaccharide from Bifidobacterium breve NCIM 5671

AIM

To evaluate the structure and functions of capsular exopolysaccharide (CPS) from Bifidobacterium breve NCIM 5671.

METHODS AND RESULTS

A CPS produced by the probiotic bacteria B. breve NCIM 5671 was isolated and subjected to characterization through GC analysis, which indicated the presence of rhamnose, fucose, galactose, and glucose in a molar ratio of 3:1:5:3. The average molecular weight of the CPS was determined to be ∼8.5 × 105 Da. Further, NMR analysis revealed the probable CPS structure to be composed of major branched tetra- and penta-saccharide units alternately repeating and having both α- and β-configuration sugar residues. CPS displayed an encouraging prebiotic score for some of the studied probiotic bacteria. Compared to standard inulin, CPS showed better resistance to digestibility against human GI tract in vitro. DPPH, total antioxidant, and ferric reducing assays carried out for CPS displayed decent antioxidant activity too.

CONCLUSION

This study indicates that the CPS from B. breve NCIM 5671 has the potential to be utilized as a prebiotic food supplement. It is a high-molecular-weight (∼8.5 × 105 Da) capsular heteropolysaccharide containing rhamnose, fucose, galactose, and glucose.

Exploring probiotic effector molecules and their mode of action in gut-immune interactions

Probiotics, live microorganisms that confer health benefits when consumed in adequate amounts, have gained significant attention for their potential therapeutic applications. The beneficial effects of probiotics are believed to stem from their ability to enhance intestinal barrier function, inhibit pathogens, increase beneficial gut microbes, and modulate immune responses. However, clinical studies investigating the effectiveness of probiotics have yielded conflicting results, potentially due to the wide variety of probiotic species and strains used, the challenges in controlling the desired number of live microorganisms, and the complex interactions between bioactive substances within probiotics. Bacterial cell wall components, known as effector molecules, play a crucial role in mediating the interaction between probiotics and host receptors, leading to the activation of signaling pathways that contribute to the health-promoting effects. Previous reviews have extensively covered different probiotic effector molecules, highlighting their impact on immune homeostasis. Understanding how each probiotic component modulates immune activity at the molecular level may enable the prediction of immunological outcomes in future clinical studies. In this review, we present a comprehensive overview of the structural and immunological features of probiotic effector molecules, focusing primarily on Lactobacillus and Bifidobacterium. We also discuss current gaps and limitations in the field and propose directions for future research to enhance our understanding of probiotic-mediated immunomodulation.