Characterization, Anti-Inflammatory and Antiproliferative Activities of Natural and Sulfonated Exo-Polysaccharides from Streptococcus thermophilus ASCC 1275

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.

Microbial exopolysaccharides: Unveiling the pharmacological aspects for therapeutic advancements

Microbial exopolysaccharides (EPSs) have emerged as a fascinating area of research in the field of pharmacology due to their diverse and potent biological activities. This review paper aims to provide a comprehensive overview of the pharmacological properties exhibited by EPSs, shedding light on their potential applications in various therapeutic areas. The review begins by introducing EPSs, exploring their various sources, significance in microbial growth and survival, and their applications across different industries. Subsequently, a thorough examination of the pharmaceutical properties of microbial EPSs unveils their antioxidant, immunomodulatory, antimicrobial, antidepressant, antidiabetic, antiviral, antihyperlipidemic, hepatoprotective, anti-inflammatory, and anticancer activities. Mechanistic insights into how different EPSs exert these therapeutic effects have also been discussed in this review. The review also provides comprehensive information about the monosaccharide composition, backbone, branches, glycosidic bonds, and molecular weight of pharmacologically active EPSs from various microbial sources. Furthermore, the factors that can affect the pharmacological activities of EPSs and approaches to improve the EPSs' pharmacological activity have also been discussed. In conclusion, this review illuminates the immense pharmaceutical promise of microbial EPS as versatile bioactive compounds with wide-ranging therapeutic applications. By elucidating their structural features, biological activities, and potential applications, this review aims to catalyze further research and development efforts in leveraging the pharmaceutical potential of microbial EPS for the advancement of human health and well-being, while also contributing to sustainable and environmentally friendly practices in the pharmaceutical industry.

Heat-Killed Enterococcus faecium KU22001 Having Effective Anti-Cancer Effects on HeLa Cell Lines at a Lower Temperature

The anti-cancer effects of heat-killed Enterococcus faecium KU22001 (KU22001), KU22002, and KU22005 isolated from human infant feces were investigated. The anti-proliferative activity of these strains against various cancer cell lines was evaluated using the MTT assay. To determine the production of exopolysaccharides (EPS) with potential anti-cancer effect, ethanol precipitation and phenol-sulfuric acid method was used with the cell free supernatant of strains grown at 25°C or 37°C. The EPS yield of E. faecium strains was higher at 25°C than at 37°C. Among these E. faecium strains, KU22001 grown at 25°C was associated with the highest bax/bcl-2 ratio, effective apoptosis rate, cell cycle arrest in the G0/G1 phase, and condensation of the nucleus in the cervical cancer HeLa cell line. In conclusion, these results suggest that KU22001 can be beneficial owing to the anti-cancer effects and production of functional materials, such as EPS.

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.

Streptococcus thermophilus: A Source of Postbiotics Displaying Anti-Inflammatory Effects in THP 1 Macrophages

In addition to traditional use in fermented dairy products, S. thermophilus also exhibits anti-inflammatory properties both in live and heat-inactivated form. Recent studies have highlighted that some hydrolysates from surface proteins of S. thermophilus could be responsible partially for overall anti-inflammatory activity of this bacterium. It was hypothesized that anti-inflammatory activity could also be attributed to peptides resulting from the digestion of intracellular proteins of S. thermophilus. Therefore, total intracellular proteins (TIP) from two phenotypically different strains, LMD-9 and CNRZ-21N, were recovered by sonication followed by ammonium sulphate precipitation. The molecular masses of the TIP of both strains were very close to each other as observed by SDS-PAGE. The TIP were fractionated by size exclusion fast protein liquid chromatography to obtain a 3-10 kDa intracellular protein (IP) fraction, which was then hydrolysed with pancreatic enzyme preparation, Corolase PP. The hydrolysed IP fraction from each strain exhibited anti-inflammatory activity by modulating pro-inflammatory mediators, particularly IL-1β in LPS-stimulated THP-1 macrophages. However, a decrease in IL-8 secretion was only observed with hydrolysed IP fraction from CNRZ-21N, indicating that strain could be an important parameter in obtaining active hydrolysates. Results showed that peptides from the 3-10 kDa IP fraction of S. thermophilus could therefore be considered as postbiotics with potential beneficial effects on human health. Thus, it can be used as a promising bioactive ingredient for the development of functional foods to prevent low-grade inflammation.

Sulfated polysaccharides from Caulerpa lentillifera: Optimizing the process of extraction, structural characteristics, antioxidant capabilities, and anti-glycation properties

The polysaccharides found in Caulerpa lentillifera (sea grape algae) are potentially an important bioactive resource. This study makes use of RSM (response surface methodology) to determine the optimal conditions for the extraction of valuable SGP (sea grape polysaccharides). The findings indicated that a water/raw material ratio of 10:1 mL/g, temperature of 90 °C, and extraction time of 45 min would maximize the yield, with experimentation achieving a yield of 21.576 %. After undergoing purification through DEAE-52 cellulose and Sephacryl S-100 column chromatography, three distinct fractions were obtained, namely SGP11, SGP21, and SGP31, each possessing average molecular weights of 38.24 kDa, 30.13 kDa, and 30.65 kDa, respectively. Following characterization, the fractions were shown to comprise glucose, galacturonic acid, xylose, and mannose, while the sulfate content was in the range of 12.2-21.8 %. Using Fourier transform infrared spectroscopy (FT-IR) it was possible to confirm with absolute certainty the sulfate polysaccharide attributes of SGP11, SGP21, and SGP31. NMR (nuclear magnetic resonance) findings made it clear that SGP11 exhibited α-glycosidic configurations, while the configurations of SGP21 and SGP31 were instead β-glycosidic. The in vitro antioxidant assays which were conducted revealed that each of the fractions was able to demonstrate detectable scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cations. All fractions were also found to exhibit the capacity to scavenge NO radicals in a dose-dependent manner. SGP11, SGP21, and SGP31 were also able to display cellular antioxidant activity (CAA) against the human adenocarcinoma colon (Caco-2) cell line when oxidative damage was induced. The concentration levels were found to govern the extent of such activity. Moreover, purified SGP were found to exert strong inhibitory effects upon glycation, with the responses dependent upon dosage, thus confirming the potential for SGP to find a role as a natural resource for the production of polysaccharide-based antioxidant drugs, or products to promote improved health.

In vitro studies on the pharmacological potential, anti-tumor, antimicrobial, and acetylcholinesterase inhibitory activity of marine-derived Bacillus velezensis AG6 exopolysaccharide

In the current study, Bacillus velezensis AG6 was isolated from sediment samples in the Red Sea, identified by traditional microbiological techniques and phylogenetic 16S rRNA sequences. Among eight isolates screened for exopolysaccharide (EPS) production, the R6 isolate was the highest producer with a significant fraction of EPS (EPSF6, 5.79 g L-1). The EPSF6 molecule was found to have a molecular weight (Mw) of 2.7 × 104 g mol-1 and a number average (Mn) of 2.6 × 104 g mol-1 when it was analyzed using GPC. The FTIR spectrum indicated no sulfate but uronic acid (43.8%). According to HPLC, the EPSF6 fraction's monosaccharides were xylose, galactose, and galacturonic acid in a molar ratio of 2.0 : 0.5 : 2.0. DPPH, H2O2, and ABTS tests assessed EPSF6's antioxidant capabilities at 100, 300, 500, 1000, and 1500 μg mL-1 for 15, 60, 45, and 60 minutes. The overall antioxidant activities were dose- and time-dependently increased, and improved by increasing concentrations from 100 to 1500 μg mL-1 after 60 minutes and found to be 91.34 ± 1.1%, 80.20 ± 1.4% and 75.28 ± 1.1% respectively. Next, EPSF6 displayed considerable inhibitory activity toward the proliferation of six cancerous cell lines. Anti-inflammatory tests were performed using lipoxygenase (5-LOX) and cyclooxygenase (COX-2). An MTP turbidity assay method was applied to show the ability of EPSF6 to inhibit Gram-positive bacteria, Gram-negative bacteria, and antibiofilm formation. Together, this study sheds light on the potential pharmacological applications of a secondary metabolite produced by marine Bacillus velezensis AG6. Its expected impact on human health will increase as more research and studies are conducted globally.

Structural elucidation of the exopolysaccharide from Streptococcus thermophilus XJ53 and the effect of its molecular weight on immune activity

EPS53, a homogeneous exopolysaccharide (EPS) was isolated from Streptococcus thermophiles XJ53 fermented in skimmed milk via anion exchange column chromatography. The relative molecular weight of EPS53 was above 6.7 × 10⁵ g/mol; its repeating structural unit of EPS53 consisted of β-T-Galp, β-1,3-Galf, α-1,3-Glcp and β-1,3,6-Glcp residues in a molar ratio of 1:1:1:1, with β-T-Galp attached to the O-6 position of β-1,3,6-Glcp，identical to the EPS produced from S. thermophilus SFi39. EPS53-D, purified under similar conditions as EPS53 except for the deproteinization of trichloroacetic acid (TCA), had a lower molecular weight but the same repeating structural unit. The effects of EPS53 and EPS53-D on proliferation, phagocytosis and nitric oxide (NO) release of macrophage RAW264.7 were compared. EPS53 exhibited stronger immune activity than EPS53-D, suggesting that the molecular weight might have an important effect on the activity of EPS molecules. Treatment with TCA might affect the activities of native EPSs produced by fermentation.

Bacterial Exopolysaccharides as Emerging Bioactive Macromolecules: From Fundamentals to Applications

Microbial exopolysaccharides (EPS) are extracellular carbohydrate polymers forming capsules or slimy coating around the cells. EPS can be secreted by various bacterial genera that can help bacterial cells in attachment, environmental adaptation, stress tolerance and are an integral part of microbial biofilms. Several gut commensals (e.g., Lactobacillus, Bifidobacterium) produce EPS that possess diverse bioactivities. Bacterial EPS also has extensive commercial applications in the pharmaceutical and food industries. Owing to the structural and functional diversity, genetic and metabolic engineering strategies are currently employed to increase EPS production. Therefore, the current review provides a comprehensive overview of the fundamentals of bacterial exopolysaccharides, including their classification, source, biosynthetic pathways, and functions in the microbial community. The review also provides an overview of the diverse bioactivities of microbial EPS, including immunomodulatory, anti-diabetic, anti-obesity, and anti-cancer properties. Since several gut microbes are EPS producers and gut microbiota helps maintain a functional gut barrier, emphasis has been given to the intestinal-level bioactivities of the gut microbial EPS. Collectively, the review provides a comprehensive overview of microbial bioactive exopolysaccharides.

Anticancer activity of lactic acid bacteria

Lactic acid bacteria (LAB), a group of Gram-positive microorganisms naturally occurring in fermented food products and used as probiotics, have been gaining the interest of researchers for years. LAB are potent, albeit still not wholly understood, source of bioactive compounds with various functions and activity. Metabolites of LAB, among others, short-chain fatty acids, exopolysaccharides and bacteriocins have promising anticancer potential. Research on the interactions between the bioactive metabolites of LAB and immune mechanisms demonstrated that these substances could exert a strong immunomodulatory effect, which would explain their vast therapeutic potential. The anticancer activity of LAB was confirmed both in vitro and in animal models against cancer cells from various malignancies. LAB inhibit tumor growth through various mechanisms, including antiproliferative activity, induction of apoptosis, cell cycle arrest, as well as through antimutagenic, antiangiogenic and anti-inflammatory effects. The aim of this review was to summarize the most recent data about the anticancer activity of LAB, with particular emphasis on the most promising bioactive compounds with potential clinical application.

Assessment of Pharmacological Potential of Novel Exopolysaccharide Isolated from Marine Kocuria sp. Strain AG5: Broad-Spectrum Biological Investigations

With more than 17 clinically approved Drugs and over 20 prodrugs under clinical investigations, marine bacteria are believed to have a potential supply of innovative therapeutic bioactive compounds. In the current study, Kocuria sp. strain AG5 isolated from the Red Sea was identified and characterized by biochemical and physiological analysis, and examination of a phylogenetic 16S rRNA sequences. Innovative exopolysaccharide (EPS) was separated from the AG5 isolate as a major fraction of EPS (EPSR5, 6.84 g/L⁻¹). The analysis of EPSR5 revealed that EPSR5 has a molecular weight (Mw) of 4.9 × 10⁴ g/mol and number average molecular weight (Mn) of 5.4 × 10⁴ g/mol and contains sulfate (25.6%) and uronic acid (21.77%). Analysis of the monosaccharide composition indicated that the EPSR5 fraction composes of glucose, galacturonic acid, arabinose, and xylose in a molar ratio of 2.0:0.5:0.25:1.0, respectively. Assessment of the pharmacological potency of EPSR5 was explored by examining its cytotoxicity, anti-inflammatory, antioxidant, and anti-acetylcholine esterase influences. The antioxidant effect of EPSR5 was dose- and time-dependently increased and the maximum antioxidant activity (98%) was observed at 2000 µg/mL after 120 min. Further, EPSR5 displayed a significant repressive effect regarding the proliferation of HepG-2, A-549, HCT-116, MCF7, HEP2, and PC3 cells with IC₅₀ 453.46 ± 21.8 µg/mL, 873.74 ± 15.4 µg/mL, 788.2 ± 32.6 µg/mL, 1691 ± 44.2 µg/mL, 913.1 ± 38.8 µg/mL, and 876.4 ± 39.8 µg/mL, respectively. Evaluation of the inhibitory activity of the anti-inflammatory activity of EPSR5 indicated that EPSR5 has a significant inhibitory activity toward lipoxygenase (5-LOX) and cyclooxygenase (COX-2) activities (IC₅₀ 15.39 ± 0.82 µg/mL and 28.06 ± 1.1 µg/mL, respectively). Finally, ESPR5 presented a substantial hemolysis suppressive action with an IC₅₀ of 65.13 ± 0.89 µg /mL, and a considerable inhibitory activity toward acetylcholine esterase activity (IC₅₀ 797.02 μg/mL). Together, this study reveals that secondary metabolites produced by Kocuria sp. strain AG5 marine bacteria serve as an important source of pharmacologically active compounds, and their impact on human health is expected to grow with additional global work and research.

Novel Exopolysaccharide from Marine Bacillus subtilis with Broad Potential Biological Activities: Insights into Antioxidant, Anti-Inflammatory, Cytotoxicity, and Anti-Alzheimer Activity

In the presented study, Bacillus subtilis strain AG4 isolated from marine was identified based on morphological, physiological, phylogenetic characteristics and an examination of 16S rRNA sequences. Novel exopolysaccharide (EPSR4) was extracted and isolated from the Bacillus subtilis strain as a major fraction of exopolysaccharide (EPS). The analysis of structural characterization indicated that EPSR4 is a β-glycosidic sulphated heteropolysaccharide (48.2%) with a molecular weight (Mw) of 1.48 × 104 g/mole and has no uronic acid. Analysis of monosaccharide content revealed that EPSR4 consists of glucose, rhamnose and arabinose monosaccharide in a molar ratio of 5:1:3, respectively. Morphological analysis revealed that EPSR4 possess a high crystallinity degree with a significant degree of porosity, and its aggregation and conformation in the lipid phase might have a significant impact on the bioactivity of EPSR4. The biological activity of EPSR4 was screened and evaluated by investigating its antioxidant, cytotoxicity, anti-inflammatory, and anti-Alzheimer activities. The antioxidant activity results showed that EPSR4 has 97.6% scavenging activity toward DPPH free radicals at 1500 µg/mL, with an IC50 value of 300 µg/mL, and 64.8% at 1500 µg/mL toward hydrogen peroxide free radicals (IC50 = 1500 µg/mL, 30 min). Furthermore, EPSR4 exhibited considerable inhibitory activity towards the proliferation of T-24 (bladder carcinoma), A-549 (lung cancer) and HepG-2 (hepatocellular carcinoma) cancer cell lines with IC50 of 244 µg/mL, 148 µg/mL and 123 µg/mL, respectively. An evaluation of anti-inflammatory activity revealed that EPSR4 has potent lipoxygenase (LOX) inhibitory activity (IC50 of 54.3 µg/mL) and a considerable effect on membrane stabilization (IC50 = 112.2 ± 1.2 µg/mL), while it showed cyclooxygenase (COX2) inhibitory activity up to 125 µg/mL. Finally, EPSR4 showed considerable inhibitory activity towards acetylcholine esterase activity. Taken together, this study reveals that Bacillus subtilis strain AG4 could be considered as a potential natural source of novel EPS with potent biological activities that would be useful for the healthcare system.

Structure characterization, antioxidant and emulsifying capacities of exopolysaccharide derived from Tetragenococcus halophilus SNTH-8

Tetragenococcus halophilus exopolysaccharides (THPS) are metabolites released by T. halophilus SNTH-8 to resist a high-salt environment. Although many studies have investigated the mechanisms underlying salt tolerance shown by T. halophilus, structural characteristics as well as antioxidant and emulsifying capacities of THPS remain unclear. In this study, we isolated and purified two components, THPS-1 and THPS-2, from T. halophilus SNTH-8. Purified THPS-1 and THPS-2 were composed of arabinose, xylose, fucose, galactose, glucose, and glucuronic acid at a molar ratio of 1.66:38.95:2.11:26.12:29.73:1.43 and 0.46:40.3:0.54:30.8:1.36:25.54, respectively. The average molecular weights of THPS-1 and THPS-2 were 14.98 kDa and 21.03 kDa, respectively. Moreover, the structures of THPS-1 and THPS-2 were investigated via fourier-transform infrared spectroscopy(FT-IR), nuclear magnetic resonance spectroscopy(NMR), scanning electron microscopy(SEM), and methylation analysis. THPS-1 was a highly branched polysaccharide with a backbone of α-D-(1,4)-Xyl, α-D-(1,6)-Glc and α-D-Xyl as the terminal, while THPS-2 was a highly branched polysaccharide with a backbone of α-D-(1,4)-Xyl and β-D-GlcA as the terminal. The branches were identified as β-D-(1,4,6)-Gal and β-D-(1,6)-Gal. Both THPS-1 and THPS-2 exhibited high antioxidant and emulsifying capacities. Overall, our structural analysis of THPS may further enhance research on natural emulsifiers and antioxidants.

Biological Functions of Exopolysaccharides from Lactic Acid Bacteria and Their Potential Benefits for Humans and Farmed Animals

Lactic acid bacteria (LAB) synthesize exopolysaccharides (EPS), which are structurally diverse biopolymers with a broad range of technological properties and bioactivities. There is scientific evidence that these polymers have health-promoting properties. Most commercialized probiotic microorganisms for consumption by humans and farmed animals are LAB and some of them are EPS-producers indicating that some of their beneficial properties could be due to these polymers. Probiotic LAB are currently used to improve human health and for the prevention and treatment of specific pathologic conditions. They are also used in food-producing animal husbandry, mainly due to their abilities to promote growth and inhibit pathogens via different mechanisms, among which the production of EPS could be involved. Thus, the aim of this review is to discuss the current knowledge of the characteristics, usage and biological role of EPS from LAB, as well as their postbiotic action in humans and animals, and to predict the future contribution that they could have on the diet of food animals to improve productivity, animal health status and impact on public health.

In Vitro Assessment of Antistaphylococci, Antitumor, Immunological and Structural Characterization of Acidic Bioactive Exopolysaccharides from Marine Bacillus cereus Isolated from Saudi Arabia

A strain of Bacillus cereus was isolated from the Saudi Red Sea coast and identified based on culture features, biochemical characteristics, and phylogenetic analysis of 16S rRNA sequences. EPSR3 was a major fraction of exopolysaccharides (EP_S) containing no sulfate and had uronic acid (28.7%). The monosaccharide composition of these fractions is composed of glucose, galacturonic acid, and arabinose with a molar ratio of 2.0: 0.8: 1.0, respectively. EPSR3 was subjected to antioxidant, antitumor, and anti-inflammatory activities. The results revealed that the whole antioxidant activity was 90.4 ± 1.6% at 1500 µg/mL after 120 min. So, the IC₅₀ value against DPPH radical found about 500 µg/mL after 60 min. While using H₂O₂, the scavenging activity was 75.1 ± 1.9% at 1500 µg/mL after 60 min. The IC₅₀ value against H₂O₂ radical found about 1500 µg/mL after 15 min. EPSR3 anticytotoxic effect on the proliferation of (Bladder carcinoma cell line) (T-24), (human breast carcinoma cell line) (MCF-7), and (human prostate carcinoma cell line) (PC-3) cells. The calculated IC50 for cell line T-24 was 121 ± 4.1 µg/mL, while the IC₅₀ for cell line MCF-7 was 55.7 ± 2.3 µg/mL, and PC-3 was 61.4 ± 2.6 µg/mL. Anti-inflammatory activity was determined for EPSR3 using different methods as Lipoxygenase (LOX) inhibitory assay gave IC₅₀ 12.9 ± 1.3 µg/mL. While cyclooxygenase (COX-2) inhibitory test showed 29.6 ± 0.89 µg /mL. EPSR3 showed potent inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci. The exposure times of EPSR3 for the complete inhibition of cell viability of methicillin resistant S. aureus was found to be 5% at 60 min. Membrane stabilization inhibitory gave 35.4 ± 0.67 µg/mL. EPSR3 has antitumor activity with a reasonable margin of safety. The antitumor activity of EPSR3 may be attributed to its content from uronic acids with potential for cellular antioxidant and anticancer functional properties.

Sulfur functionality-modified starches: Review of synthesis strategies, properties, and applications

Starch is the second most abundant naturally-occurring polymer after cellulose that possess superior physicochemical and biological features with numerous practical applications ranging from industrial to biomedical. Despite, native starch suffer from some drawbacks, including difficult processability, low shear and thermal stability, weak mechanical properties, and tendency to easily retrograde and undergo syneresis. Therefore, modification of native starch is necessary for circumvent the above-mentioned problems and expanding application ranges. This natural polymer can be modified using chemical, physical, enzymatic, and genetic engineering strategies. Amongst, chemical approaches have received more attention owing to enhancing physicochemical and biological features that lead to higher performance than those of the other strategies. In this context, incorporation of sulfur functionality-containing groups (sulfonation and sulfation) can be considered as an efficient approach due to significant enhancement in physiochemical properties, including zeta potential (move to negative values), molecular weight, processiability (e.g., solubility and meltability), and rheology. Furthermore, this strategy can modified some biological features, such as hemocompatibility, protein sorption, biostability, adhesion and proliferation of numerous cells, antithrombogenicity, antiinflammatory, antiviral, antimicrobial, antioxidant, antifungal, anticoagulant and antifouling properties. Accordingly, this review highlight's the synthesis strategies, physiochemical and biological properties, as well as applications of sulfur functionality-modified starches in numerous practical fields.

In Vitro Immunomodulation of the Polysaccharides from Yam (Dioscorea opposita Thunb.) in Response to a Selenylation of Lower Extent

The immunomodulation of chemically selenylated polysaccharides has been attracting more attention recently, but the corresponding performance of the yam polysaccharides (YPS) with lower selenylation extent remains, thus far, unsolved. In this study, the YPS was selenylated with Na₂SeO₃ under acidic conditions generated by HNO₃ to reach two lower selenylation extents, yielding two selenylated YPSs, namely SeYPS-1 and SeYPS-2 with selenium contents of 715 and 1545 mg/kg, respectively. The results indicated that YPS, SeYPS-1, and SeYPS-2 all had in vitro immuno-modulation when using RAW 264.7 macrophages and murine splenocytes as cell models. In detail, the three polysaccharide samples at dose levels of 5–160 μg/mL showed insignificant cytotoxicity to the macrophages and splenocytes with cell exposure times of 12–24 h, because of the measured values of cell viability larger than 100%. However, Na₂SeO₃ at dose levels of 1.3–3.25 μg/mL mostly caused obvious cytotoxic effects on the cells, resulting in reduced cell viability values or cell death, efficiently. The results demonstrated that, compared with YPS, both SeYPS-1 and SeYPS-2 at a lower dose level (5 μg/mL) were more active at promoting phagocytosis activity, increasing the CD4⁺/CD8⁺ ratio of the T-lymphocyte sub-population in the murine splenocyte, improving cytokine secretion, including interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α in the macrophages, or increasing interferon-γ secretion, but suppressing IL-4 production in the splenocytes. Consistently, SeYPS-2 has more potential than SeYPS-1 at exerting these assessed bioactivities in the cells. Thus, we conclude that a chemical modification of YPS using trace element Se at a lower selenylation extent could bring about higher immunomodulatory activity towards macrophages and splenocytes, while selenylation extent of YPS is a critical factor used to govern the assessed activity changes of YPS.

Seaweed polysaccharides: Emerging extraction technologies, chemical modifications and bioactive properties

Nowadays, consumers are increasingly aware of the relationship between diet and health, showing a greater preference of products from natural origin. In the last decade, seaweeds have outlined as one of the natural sources with more potential to obtain bioactive carbohydrates. Numerous seaweed polysaccharides have aroused the interest of the scientific community, due to their biological activities and their high potential on biomedical, functional food and technological applications. To obtain polysaccharides from seaweeds, it is necessary to find methodologies that improve both yield and quality and that they are profitable. Nowadays, environmentally friendly extraction technologies are a viable alternative to conventional methods for obtaining these products, providing several advantages like reduced number of solvents, energy and time. On the other hand, chemical modification of their structure is a useful approach to improve their solubility and biological properties, and thus enhance the extent of their potential applications since some uses of polysaccharides are still limited. The present review aimed to compile current information about the most relevant seaweed polysaccharides, available extraction and modification methods, as well as a summary of their biological activities, to evaluate knowledge gaps and future trends for the industrial applications of these compounds.Key teaching pointsStructure and biological functions of main seaweed polysaccharides.Emerging extraction methods for sulfate polysaccharides.Chemical modification of seaweeds polysaccharides.Potential industrial applications of seaweed polysaccharides.Biological activities, knowledge gaps and future trends of seaweed polysaccharides.

The anti-cancer effects and mechanisms of lactic acid bacteria exopolysaccharides in vitro: A review

Probiotic lactic acid bacteria (LAB) are a particular group of gram-positive bacteria that are usually involved in natural ferments and widely used in food manufacture industry. Most of them can produce exopolysaccharides (EPS), surface carbohydrate polymers with diverse biological functions. LAB EPS are potentially complementary and alternative medicines against cancer. EPS show anti-proliferative effects on a variety of tumor cells from intestine, liver, breast, etc. They modulate the development of tumors through various mechanisms including promoting apoptosis, inducing cell cycle arrest as well as anti-mutagenic, anti-oxidative, anti-angiogenesis and anti-inflammatory effects. Bacterial origin, existence form, chemical structure, purity et al. are important factors affecting the anticancer effects of EPS. The future challenge lies in elucidating the precise structure-function relationship of LAB EPS. Besides, more in vivo studies and further clinical trials are indispensable to confirm the anticancer effects.

Structural characterization of exopolysaccharide from Streptococcus thermophilus ASCC 1275

In this study, we purified and characterized exopolysaccharide (EPS) produced by a high-EPS-producing dairy starter bacterium, Streptococcus thermophilus ASCC 1275. Crude EPS was extracted from S. thermophilus ASCC 1275 and partially purified using dialysis. Further purification and fractionation of exopolysaccharide was conducted using HPLC on a Superose 6 column (Cytiva/Global Life Sciences Solutions, Marlborough, MA). Glycosyl composition analysis, linkage analysis along with 1-dimensional and 2-dimensional nuclear magnetic resonance spectroscopy were performed to deduce the structure of EPS. Three fractions (F) obtained from gel permeation chromatography were termed F1 (2.6%), F2 (45.8%), and F3 (51.6%) with average molecular weights of approximately 511, 40, and 5 kDa, respectively. Monosaccharide composition analysis revealed the dominance of glucose, galactose, and mannose in all 3 fractions. Major linkages observed in F3 were terminal galactopyranosyl (t-Gal), 3-linked glucopyranosyl (3-Glc), 3-linked galactofuranosyl (3-Galf), and 3,6-linked glucopyranosyl (3,6-Glc) and major linkages present in F2 were 4-Glc (48 mol%), followed by terminal mannopyranosyl (t-Man), 2- + 3-linked mannopyranosyl (2-Man+3-Man), and 2,6-linked mannopyranosyl (2,6-Man; total ∼28 mol%). The 1-dimensional and 2-dimensional nuclear magnetic resonance spectroscopy revealed that F2 comprised mannans linked by (1→2) linkages and F3 consisted of linear chains of α-d-glucopyranosyl (α-d-Glcp), β-d-glucopyranosyl (β-d-Glcp), and β-d-galactofuranosyl (β-d-Galf) connected by (1→3) linkages; branching was through (1→6) linkage in F3. A possible structure of EPS in F2 and F3 was proposed.

Isolation, purification, characterization and immunostimulatory activity of an exopolysaccharide produced by Lactobacillus pentosus LZ-R-17 isolated from Tibetan kefir

In this study, three strains of lactic acid bacteria isolated from Tibetan kefir grains, including two strains of Lactobacillus pentosus LZ-R-17 and L. helveticus LZ-R-5, and one strain of Lactococcus lactis subsp. lactis LZ-R-12. The ability of three strains to produce exopolysaccharide (EPS) was tested, and L. pentosus LZ-R-17 was found to have the highest EPS yield. One EPS (R-17-EPS) was isolated from the fermented milk by L. pentosus LZ-R-17 and purified by DEAE-52 anion exchange chromatography. Furthermore, R-17-EPS preliminary structure and macrophage immunomodulatory activity in vitro were investigated. On the basis of the analytical results of ultraviolet-visible spectrum, Fourier transform-infrared spectrum, monosaccharide composition analysis and one-dimensional and two-dimensional nuclear magnetic resonance (NMR) spectra, R-17-EPS was found to have an average molecular weight of 1.20 × 106 Da and was composed of galactose and glucose residues with a molar ratio of 1.00:3.15. NMR analysis revealed that the R-17-EPS was a linear hetero-galactoglucan containing repeating units of →2)-α-D-Galp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Glcp-(1→. In addition, R-17-EPS could effectively enhanced the proliferation, phagocytosis, nitric oxide and cytokines production of RAW264.7 cells, suggesting that R-17-EPS had potent immunostimulatory activity and could be explored as immunomodulator in functional food and/or medicine fields.

Proteomic analysis reveals potential factors associated with enhanced EPS production in Streptococcus thermophilus ASCC 1275

Streptococcus thermophilus ASCC 1275 has two chain length determining genes - epsC and epsD- in its eps gene cluster, and produces two times more EPS in sucrose medium than that in glucose and lactose. Hence, we investigated the influence of sugars (glucose, sucrose and lactose), at log phase (5 h) and stationary phase (10 h), on the global proteomics of S. thermophilus 1275 to understand the differentially expressed proteins (DEPs) during EPS production using isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomic analysis. Among 98 DEPs in sucrose medium, most of them were mapped into EPS biosynthesis pathway and other related metabolisms. There was an upregulation of several proteins involved in sugar transport (phosphoenolpyruvate (PEP) phosphotransferase system), EPS assembly (epsG1D) and amino acid metabolism (methionine, cysteine/arginine metabolism) in sucrose medium. This study showed that increased EPS production in S. thermophilus 1275 requires a well-co-ordinated regulation of pathway involved in both EPS assembly and amino acid metabolism along with the availability of sugars. Thus, it provided valuable insights into the biosynthesis and regulation of EPS in S. thermophilus 1275, and potential gene targets for understanding high-EPS strains.

Anti-inflammatory activity and structural identification of a sulfated polysaccharide CLGP4 from Caulerpa lentillifera

In the present study, the in vitro anti-inflammatory activity of four purified polysaccharides (CLGP1, CLGP2, CLGP3 and CLGP4) extracted from edible green algae Caulerpa lentillifera was evaluated. As a result, CLGP4 exhibited more effectively inhibitory effect on LPS-induced HT29 cells, including reducing the production of IL-1β, TNF-α, SIgA and mucin2, and decreasing the expression of IL-1β and TNF-α. According to the results, CLGP4 showed a better anti-inflammatory effect, might highly related to the presence of sulfate groups. Furthermore, the structure of CLGP4 was analyzed by methylation analysis, GC-MS and NMR spectroscopy. It was found that CLGP4 was a novel xylogalactomanan consisting of β-(1 → 4)-Man_p, →2,4)Man_p(1→, β-(1 → 2)-Man_p, β-(1 → 3)-Gal_p, β-(1 → 4)-Xyl_p, terminal β-Gal_p and terminal β-Xyl_p residues. Additionally, the sulfate groups were located on C-3 of →4)Xyl_p(1→, C-6 of →3)Gal_p(1→ and C-3 of →2)Man_p(1→. These results could enlarge the potential application of CLGP4 as functional ingredient to attenuate inflammation.

Functional Genomic Analyses of Exopolysaccharide-Producing Streptococcus thermophilus ASCC 1275 in Response to Milk Fermentation Conditions

Exopolysaccharide (EPS) produced from dairy bacteria improves texture and functionalities of fermented dairy foods. Our previous study showed improved EPS production from Streptococcus thermophilus ASCC1275 (ST1275) by simple alteration of fermentation conditions such as pH decrease (pH 6.5 → pH 5.5), temperature increase (37°C → 40°C) and/or whey protein isolate (WPI) supplementation. The iTRAQ-based proteomics in combination with transcriptomics were applied to understand cellular protein expression in ST1275 in response to above shifts during milk fermentation. The pH decrease induced the most differentially expressed proteins (DEPs) that are involved in cellular metabolic responses including glutamate catabolism, arginine biosynthesis, cysteine catabolism, purine metabolism, lactose uptake, and fatty acid biosynthesis. Temperature increase and WPI supplementation did not induce much changes in global protein express profiles of ST1275 between comparisons of pH 5.5 conditions. Comparative proteomic analyses from pairwise comparisons demonstrated enhanced glutamate catabolism and purine metabolism under pH 5.5 conditions (Cd2, Cd3, and Cd4) compared to that of pH 6.5 condition (Cd1). Concordance analysis for differential expressed genes (DEGs) and DEPs highlighted down-regulated glutamate catabolism and up-regulated arginine biosynthesis in pH 5.5 conditions. Down regulation of glutamate catabolism was also confirmed by pathway enrichment analysis. Down-regulation of EpsB involved in EPS assembly was observed at both mRNA and protein level in pH 5.5 conditions compared to that in pH 6.5 condition. Medium pH decreased to mild acidic level induced cellular changes associated with glutamate catabolism, arginine biosynthesis and regulation of EPS assembly in ST1275.

Transcriptomic Insights Into the Growth Phase- and Sugar-Associated Changes in the Exopolysaccharide Production of a High EPS-Producing Streptococcus thermophilus ASCC 1275

In a previous study, incorporation of high exopolysaccharide (EPS) producing dairy starter bacterium Streptococcus thermophilus ASCC 1275 was found to improve functionality of low fat mozzarella cheese and yogurt. This bacterium in its eps gene cluster has a unique pair of chain length determining genes, epsC- epsD, when compared to other sequenced S. thermophilus strains. Hence, the aim of this study was to understand the regulatory mechanism of EPS production in this bacterium using transcriptomic analysis to provide opportunities to improve the yield of EPS. As sugars are considered as one of the major determinants of EPS production, after preliminary screening, we selected three sugars, glucose, sucrose and lactose to identify the EPS producing mechanism of this bacterium in M17 medium. Complete RNA-seq analysis was performed using Illumina HiSeq 2000 sequencing system on S. thermophilus 1275 grown in three different sugars at two-time points, 5 h (log phase) and 10 h (stationary phase) to recognize the genes involved in sugar uptake, UDP-sugar formation, EPS assembly and export of EPS outside the bacterial cell. S. thermophilus 1275 was found to produce high amount of EPS (∼430 mg/L) in sucrose (1%) supplemented M17 medium when compared to other two sugars. Differential gene expression analysis revealed the involvement of phosphoenolpyruvate phosphotransferase system (PEP-PTS) for glucose and sucrose uptake, and lacS gene for lactose uptake. The pathways for the formation of UDP-glucose and UDP-galactose were highly upregulated in all the three sugars. In the presence of sucrose, eps1C1D2C2D were found to be highly expressed which refers to high EPS production. Protein homology study suggested the presence of Wzx/Wzy-dependent EPS synthesis and transport pathway in this bacterium. KEGG pathway and COG functional enrichment analysis were also performed to support the result. This is the first report providing the transcriptomic insights into the EPS production mechanism of a common dairy bacterium, S. thermophilus.

Rebuilding the Gut Microbiota Ecosystem

A microbial ecosystem in which bacteria no longer live in a mutualistic association is called dysbiotic. Gut microbiota dysbiosis is a condition related with the pathogenesis of intestinal illnesses (irritable bowel syndrome, celiac disease, and inflammatory bowel disease) and extra-intestinal illnesses (obesity, metabolic disorder, cardiovascular syndrome, allergy, and asthma). Dysbiosis status has been related to various important pathologies, and many therapeutic strategies aimed at restoring the balance of the intestinal ecosystem have been implemented. These strategies include the administration of probiotics, prebiotics, and synbiotics; phage therapy; fecal transplantation; bacterial consortium transplantation; and a still poorly investigated approach based on predatory bacteria. This review discusses the various aspects of these strategies to counteract intestinal dysbiosis.

Comparative mRNA-Seq Analysis Reveals the Improved EPS Production Machinery in Streptococcus thermophilus ASCC 1275 During Optimized Milk Fermentation

Exo-polysaccharide (EPS) produced by dairy starters plays critical roles in improving texture and functionalities of fermented dairy products. One of such high EPS producers, Streptococcus thermophilus ASCC 1275 (ST1275) was used as a model dairy strain to understand the stimulation of its EPS production under optimal milk fermentation conditions. The mRNA-seq analysis and targeted pathway analysis indicate that genes associated with lactose (milk sugar) catabolism, EPS assembly, proteolytic activity, and arginine/methionine/cysteine synthesis and transport in ST1275 were significantly up-regulated under the optimized conditions of pH 5.5, 40°C, or WPI supplementation compared to that of pH 6.5 and 37°C, respectively. This indicates that genes involved in above metabolisms cooperate together for improving EPS yield from ST1275. This study provides a global view map on potential targeted pathways and specific genes accounted for enhanced EPS production in Str. thermophilus and that could be modulated by fermentation conditions.

Complete Genome Sequence of Streptococcus thermophilus KLDS 3.1003, A Strain with High Antimicrobial Potential against Foodborne and Vaginal Pathogens

Lactic acid bacteria play increasingly important roles in the food industry. Streptococcus thermophilus KLDS 3.1003 strain was isolated from traditional yogurt in Inner Mongolia, China. It has shown high antimicrobial activity against selected foodborne and vaginal pathogens. In this study, we investigated and analyzed its complete genome sequence. The S. thermophilus KLDS 3.1003 genome comprise of a 1,899,956 bp chromosome with a G+C content of 38.92%, 1,995 genes, and 6 rRNAs. With the exception of S. thermophilus M17TZA496, S. thermophilus KLDS 3.1003 has more tRNAs (amino acid coding genes) compared to some S. thermophilus strains available on the National Centre for Biotechnology Information database. MG-RAST annotation showed that this strain has 317 subsystems with most genes associated with amino acid and carbohydrate metabolism. This strain also has a unique EPS gene cluster containing 23 genes, and may be a mixed dairy starter culture. This information provides more insight into the molecular basis of its potentials for further applications in the dairy and allied industries.

Sulfonation and Antioxidative Evaluation of Polysaccharides from Pleurotus Mushroom and Streptococcus thermophilus Bacteria: A Review

Human beings are equipped with antioxidant defense systems to neutralize free radicals as free radicals could damage macromolecules, subsequently resulting in serious diseases. Researchers have been attracted to search for potential natural antioxidants to reduce oxidative damage. Pleurotus and Streptococcus thermophilus have been chosen as sources of sustainable bioactive compounds that have been consumed for thousands of years. Polysaccharides are important bioactive components produced by Pleurotus mushrooms and Streptococcus thermophilus bacteria. Additionally, there is a continued interest in sulfonation of crude polysaccharides from both sources, since sulfonation has been found to improve or create new bioactive properties in polysaccharides. Both crude and sulfated polysaccharides with good antioxidant capacities have great potential for the further development as commercial products. This review focuses on characterization, sulfonation methods, and antioxidant capacity evaluations of polysaccharides from Pleurotus and S. thermophilus. Common antioxidant capacity assays, including the mechanisms underlying each assay, and various experimental procedures are also discussed.