Search Results (432)

Cyanobacteria are a prolific source of bioactive metabolites with expanding applications in sustainable agriculture and biotechnology. This work explores, for the first time in thermotolerant Colombian isolates, the impact of light spectrum, photoperiod, and irradiance on the co-production of exopolysaccharides (EPS) and indole-3-acetic acid (IAA). Six strains from hot-spring environments were screened under varying blue:red (B:R) LED ratios and full-spectrum illumination. Hapalosiphon sp. UFPS_002 outperformed all others, reaching ~290 mg L⁻¹ EPS and 28 µg mL⁻¹ IAA in the initial screen. Response-surface methodology was then used to optimize light intensity and photoperiod. EPS peaked at 281.4 mg L⁻¹ under a B:R ratio of 1:5 LED, 85 µmol m⁻² s⁻¹, and a 14.5 h light cycle, whereas IAA was maximized at 34.4 µg mL⁻¹ under cool-white LEDs at a similar irradiance. The quadratic models exhibited excellent predictive power (R² > 0.98) and a non-significant lack of fit, confirming the light regime as the dominant driver of metabolite yield. These results demonstrate that precise photonic tuning can selectively steer carbon flux toward either EPS or IAA, providing an energy-efficient strategy to upscale thermotolerant cyanobacteria for climate-resilient biofertilizers, bioplastics precursors, and other high-value bioproducts. Full article

Porphyra-derived polysaccharides (PPs) are promising prebiotic candidates due to their capacity to modulate gut microbiota and promote host health. However, their interactions with and utilization by probiotic microorganisms remain unclear. In this study, the fermentability of PPs by murine-derived lactic acid bacteria (LAB) strains was investigated, with particular attention to strain-specific metabolic activity, carbohydrate utilization, and potential exopolysaccharide (EPS) production. All tested strains were capable of utilizing PPs to varying extents, with strain A10 exhibiting the highest level of carbohydrate consumption. Notably, strain A5 showed increased mannose concentrations following fermentation, suggesting the biosynthesis of mannose-rich EPSs. HPLC analysis confirmed the presence of high-molecular-weight polysaccharides ranging from 2.6 to 8.1 × 10⁵ Da, indicative of EPS production. FT-IR spectroscopy further revealed spectral features consistent with EPS structures. The antibacterial activity of postbiotic compounds produced by LAB strains fermenting PPs against Escherichia coli and Staphylococcus aureus was observed. These findings demonstrate distinct metabolic adaptations of LAB strains to PPs and emphasize their potential as prebiotic substrates. Full article

The exopolysaccharide (EPS) produced by Leuconostoc mesenteroides SJC113 is a glucan with α-1,6 and α-3,6 branched glycosidic linkages that may promote human health. The aim of this study was to investigate in vitro the antioxidant, cholesterol-binding, and prebiotic activities of this EPS and its effect on the gut microbiota. The EPS exhibited moderate antioxidant activity, showing free radical scavenging activity (10.94 ± 1.33%) and hydroxyl scavenging activity (6.29 ± 1.59%) at 1 mg/mL. Notably, it showed high cholesterol-binding activity, lowering cholesterol levels by 40% at 1 mg/mL EPS. Ln. mesenteroides SJC113 showed strong adhesion to mucin, and its EPS enhanced the adhesion of the probiotic Lacticaseibacillus rhamnosus GG. The application of this EPS stimulated the growth of several lactic acid bacteria (LAB) strains in vitro, indicating its potential as a prebiotic. In addition, the use of a human gastrointestinal simulator inoculated with fecal microbiota showed that the EPS favored the growth of Bifidobacterium spp. and lactobacilli while reducing Enterobacteriaceae. These results emphasize the multifunctional nature of the EPS produced by Ln. mesenteroides SJC113 with antioxidant, cholesterol-lowering, and prebiotic properties. Further research is required to investigate the specific mechanisms of action and health benefits in vivo. Full article

This study explores the valorization of agro-industrial by-products—riceberry broken rice (RBR) and soybean meal (SBM)—as cost-effective substrates for enhancing exopolysaccharide (EPS) production by Bacillus tequilensis PS21. Eight Bacillus strains were screened, and B. tequilensis PS21 demonstrated the highest EPS yield (2.54 g/100 mL DW). The EPS displayed a strong antioxidant capacity with 65.5% DPPH and 80.5% hydroxyl radical scavenging, and a FRAP value of 6.51 mg Fe²⁺/g DW. Antimicrobial testing showed inhibition zones up to 10.07 mm against Streptococcus agalactiae and 7.83 mm against Staphylococcus aureus. Optimization using central composite design (CCD) and the response surface methodology (RSM) revealed the best production at 5% (w/v) RBR, 3% (w/v) SBM, pH 6.66, and 39.51 °C, yielding 39.82 g/L EPS. This EPS is a moderate-molecular-weight (11,282 Da) homopolysaccharide with glucose monomers. X-ray diffraction (XRD) showed an amorphous pattern, favorable for solubility in biological applications. Thermogravimetric analysis (TGA) demonstrated thermal stability up to ~250 °C, supporting its suitability for high-temperature processing. EPS also exhibited anticancer activity with IC₅₀ values of 226.60 µg/mL (MCF-7) and 224.30 µg/mL (HeLa) at 72 h, reduced colony formation, inhibited cell migration, and demonstrated anti-tyrosinase, anti-collagenase, and anti-elastase effects. This study demonstrates the successful valorization of agro-industrial by-products—RBR and SBM—for the high-yield production of multifunctional EPS with potent antioxidant, antimicrobial, and anticancer properties. The findings highlight the sustainable potential of these low-cost substrates in supporting the development of green and value-added bioproducts, with promising utilizations across the food, pharmaceutical, and cosmetic sectors. Full article

Background/Objectives: Ulcerative colitis (UC) is characterized by the interplay between immune responses and dysbiosis in disease development. Aiming to provide additional insights into disease development and potential treatment strategies, the present study investigates the local effect of oral treatment with polysaccharides obtained from Auricularia auricula’s submerged culture in an experimental model of DSS-induced colitis and its impact on lesion resolution. Methods: The structure and monosaccharide composition of Auricularia polysaccharides were characterized through Nuclear Magnetic Resonance (NMR). To evaluate the effect of this polysaccharide on the murine model, wild-type and Dectin-1 knockout mice were treated or not with the exopolysaccharide (EPS) while under DSS consumption. During the experimental period, feces samples were collected to evaluate microbial shifts during disease development, and, finally, the colonic tissue was analyzed to assess the inflammatory process and cytokine production. Results: The EPS composition showed a polymeric mixture of glucans and fucogalactomannans. The treatment of the wild-type DSS-induced colitis group improved the inflammatory response by increasing gut–homeostatic cytokines, such as interleukin-10 (IL-10) and tumor necrosis factor-alpha (TNF-α). The Dectin-1 KO mice group did not show the same enhancement after EPS treatment. The microbiome analysis revealed a difference in the genotype, and the treatment modified the DSS microbiome modulation, with nine and four ASVs in WT and Dectin-1 KO mice, respectively. Conclusions: The EPS treatment demonstrated therapeutic potential in treating inflammatory intestinal diseases by modulating cytokine secretion and microbiota composition, which is dependent on the Dectin-1 receptor’s carbohydrate recognition. Full article

Plant growth-promoting rhizobacteria (PGPR) are eco-friendly and sustainable options for agrochemicals, particularly for enhancing crop productivity under stress conditions. The present research aims to isolate and characterize native PGPR from tomato rhizospheric soil and to evaluate their effectiveness as a dose-dependent response to enhance the growth of tomato seedlings. Out of 112 isolates, 10 bacterial strains were selected based on key PGPR traits, including indole-3-acetic acid (IAA), ammonia production, hydrogen cyanide (HCN), exopolysaccharide (EPS) synthesis, hydrolytic enzyme activity, potassium solubilization, antifungal activity against Fusarium oxysporum, and tolerance to pH and heat stress. Molecular identification via 16S rRNA gene sequencing confirmed that these isolates belong to the genera Serratia and Enterobacter. S. marcescens So-1 and Enterobacter sp. So-12 produced the highest levels of IAA (2.6–24.1 µg/mL). In vitro tomato seed germination tests using bacterial suspensions at three concentrations (10⁶, 10⁷, and 10⁸ CFU/mL) showed dose-dependent improvements, with T1 increasing germination up to 108.3% compared to the control. In polyhouse trials using cocopeat formulations, seedling growth improved noticeably. T2 increased the root length (28.3 ± 2.98 cm) by over 1560%, and the shoot length (35.7 ± 0.57 cm) increased by 55% against the control, whose root length is 1.7 ± 0.47. The chlorophyll amount of the treated leaves further showed significant results over the control. Collectively, these findings suggest that using native PGPR in a dose-dependent way can help tomato seedlings grow better and promote more sustainable crop production. Full article

Objectives: This study investigated the properties of a neutral exopolysaccharide (EPS-LP1) with an average molecular weight of 55,637 Da, isolated from Lactiplantibacillus plantarum DMDL 9010 (LP9010). Results: The composition of EPS-LP1 includes galactose (Gal), glucose (Glu) and mannose (Man) in a molar ratio of 5.35:86.25:8.40. Notably, EPS-LP1 exhibits a smooth and rod-like surface along with thermal stability. Methylation combined with nuclear magnetic resonance analysis revealed that EPS-LP1 structured as t-Galp(1→, →6)-Glcp(1→, 4)-Glcp(1→ and →4,6)-Galp(1→), with relative molar ratio of 1.016:9.874:4.355:78.693:6.062, respectively. In the concentration range of 50 to 400 mg/mL, we observed the absence of cytotoxic effects from EPS-LP1 on RAW264.7 cells. Furthermore, EPS-LP1 demonstrated protective effects on RAW264.7 cells against oxidative damage by reducing the production of reactive oxygen species (ROS), malondialdehyde (MDA), and lactate dehydrogenase (LDH) release. Conversely, an increase in superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and concentrations of glutathione (GSH) was observed. Immunoreactivity assays indicated that EPS-LP1 can effectively reduce the production of nitric oxide (NO) and inhibit the secretion of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). Additionally, it inhibited the activation of the mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B gene binding (NF-kB) signaling pathway. Conclusions: This research provides a foundation basis for further investigations into the neutral exopolysaccharide derived from LP9010. Full article

In the development of high-temperature and high-salinity oil fields, biopolymer scleroglucan flooding technology faces significant challenges. Traditional scleroglucan products exhibit poor injectability and high extraction costs. This study investigated the application potential of the original fermentation broth of exopolysaccharides (EPS) produced by microorganisms in a simulated high-temperature and high-salinity oil reservoir environment. The polysaccharide was identified as scleroglucan through IR and NMR analysis. Its stability and rheological properties were comprehensively evaluated under extreme conditions, including temperatures up to 150 °C, pH levels ranging from 1 to 13, and salinities up to 22 × 10⁴ mg/L. The results demonstrated that EPS maintained excellent viscosity and stability, particularly at 76.6 °C and 22 × 10⁴ mg/L salinity, where its viscosity remained above 80% for 35 days. This highlights its significant viscoelasticity and stability in high-temperature and high-salinity oil reservoirs. Additionally, this study, for the first time, examined the rheological properties of the original fermentation broth of scleroglucan, specifically assessing its injectability and enhanced oil recovery (EOR) performance in a simulated Middle Eastern high-temperature, high-salinity, medium-low permeability reservoir environment. The findings revealed an effective EOR exceeding 15%, confirming the feasibility of using the original fermentation broth as a biopolymer for enhancing oil recovery in extreme reservoir conditions. Based on these experimental results, it is concluded that the original fermentation broth of Athelia rolfsii exhibits superior performance under high-temperature and high-salinity conditions in medium–low permeability reservoirs, offering a promising strategy for future biopolymer flooding in oil field development. Full article

This study aims to identify the chemical structure and immunomodulatory activity of exopolysaccharides (EPSs) from Acetilactobacillus jinshanensis BJ01 and suggest its potential applications in the pharmaceutical field and as functional food additives. The EPS-1 produced by A. jinshanensis BJ01 was purified using column chromatography. The lyophilized powder obtained by vacuum freeze-drying was used for structural characterization and immunomodulatory activity analysis. Gel permeation chromatography (GPC) determined its molecular weight as 156.58 kDa. High-performance anion-exchange chromatography (HPAEC) identified that the EPS-1 is composed of mannose, xylose, and glucose. The structural characterization of EPS-1 by gas chromatography–mass spectrometry (GC-MS) and 1D/2D nuclear magnetic resonance (NMR) spectroscopy demonstrated that EPS-1 is primarily composed of α-D-Manp-(1→, →2,6)-α-D-Manp-(1→, →2)-α-D-Manp-(1→, and →3)-α-D-Manp-(1→. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) illustrated that EPS-1 exhibited a round, flake-like morphology. In vitro experiments with RAW264.7 macrophages demonstrated the high immunomodulatory activity of EPS-1. Significant upregulation of iNOS, IL-6, and TNF-α mRNA levels was confirmed by qRT-PCR (p < 0.05). Western blotting revealed that EPS-1 (6.25 μg/mL) induced phosphorylation of NF-κB (p65, IκBα) and MAPK (ERK) signaling proteins. This study provides the first structural and immunomodulatory characterization of an exopolysaccharide from A. jinshanensis BJ01, highlighting its potential as a novel immune adjuvant. Full article

Heparin, a widely used polysaccharidic anticoagulant of animal origin, is associated with risks of contamination and adverse effects, notably bleeding and thrombocytopenia. These limitations have prompted interest in alternative sulfated polysaccharides with anticoagulant properties and improved safety profiles. This study explored the anticoagulant potential of two marine bacterial exopolysaccharides (EPS), infernan and diabolican. It assessed whether chemical modifications (depolymerization, oversulfation) could enhance their anticoagulant properties compared to unfractionated and low molecular weight heparins. Native EPS were depolymerized to generate different molecular weights and then chemically oversulfated to increase negative charge density. Anticoagulant activities were evaluated using clotting and thrombin generation assays (TGA). Molecular docking was performed to model interactions with antithrombin and heparin cofactor II. Only highly sulfated derivatives significantly prolonged activated partial thromboplastin time while showing negligible effect on thrombin time and anti-factor Xa activity. They present different structures, and their binding to antithrombin is not achieved via the classic pentasaccharide motif. In TGA, these derivatives inhibited thrombin formation at higher doses than heparin but induced a marked delay in clot generation. Docking analyses supported their ability to bind serpins, albeit with lower specificity than heparin. Their limited anti-Xa activity and non-animal origin position them as promising anticoagulant candidates. Full article

Egypt’s rapid population increase has resulted in higher water demand. It may significantly reduce the amount of water available for agriculture, increasing the chance of using saline water in agriculture. Using saline water certainly poses a major threat to maize growth and may severely affect the growth and productivity of this important crop. Therefore, the aim of this study was to isolate newly native salt-tolerant bacteria from Egyptian saline soils and assess their ability to produce growth-promoting substances under salinity stress, as well as test the mitigating impact of these isolated salt-tolerant bacteria along with arbuscular mycorrhizal fungi (AMF) in maize plants under salinity stress. We isolated ninety-seven salt-tolerant bacterial isolates, and these isolates show a high ability to grow under different concentrations of NaCl. The nine most efficient isolates show a high ability to produce indole acetic acid (IAA), gibberellic acid (GA), P-solubilized exopolysaccharides (EPS), proline, and antioxidants under different NaCl concentrations. Using the 16S rRNA gene, the most effective isolate STB 89 was identified, and its impact, along with AMF, on the growth of salinity-stressed maize was tested in a pot experiment. Our results showed that the growth parameters (shoot length, root length, dry weight, and leaf area), photosynthetic-related pigments (Chlorophyll a, b, and carotenoids), NPK content, and antioxidant enzymes (PPO, POX, and CAT) were improved significantly at p ≤ 0.05 due to the bioinoculant applications, while reduced proline accumulation, Na uptake, and the Na⁺/K⁺ ratio in maize plant tissues were observed compared to the control plants. Moreover, the indices of AMF colonization in maize roots and the count of bacteria in the rhizosphere were enhanced due to the bioinoculant applications under salinity stress. In addition, we found that the combined application was more pronounced than the individual application impact. Hence, our results recommended that salt-tolerant bacteria (STB 89) could support salinity, mitigating the impact of AMF in maize plants, as well as allowing better practical techniques for maize cultivation and soil sustainability under salinity stress. Full article

Vibrio harveyi, a pathogenic vibrio, is ubiquitous and the most prevalent disease infecting tropical and subtropical mariculture animals in marine and estuarine environments. It presents a major risk to mariculture companies worldwide and can cause serious disease problems in aquaculture. Recent studies have shown that various pathogens employ post-translational modifications (PTMs) to regulate cellular processes. One of the major PTMs is lysine succinylation, which is widespread in eukaryotic and prokaryotic cells. Many basic biological functions of bacteria are associated with the regulation of lysine (K) succinylation (Ksuc). However, little is known about the role of lysine succinylation in V. harveyi pathogenesis. Here, we performed LC-MS/MS analysis of 1271 proteins from V. harveyi to identify 4252 Ksuc modification sites. The modification of S-ribosylhomocysteine lyase (LuxS) and transcription elongation factor GreA proteins by Ksuc was confirmed through immunoprecipitation combined with Western blot, further validating our proteomics results. Bioinformatics study revealed that the identified Ksuc proteins play roles in multiple cellular processes and vital metabolic pathways, including LuxS, biofilm exopolysaccharide biosynthesis protein EpsG, and the general secretory system (Sec systems), and are proteins that regulate bacterial virulence. Generally, this scientific study serves as the basis for additional research on the pathogenic nature of Ksuc in V. harveyi and reveals potential targets that would accelerate the manufacturing of attenuated vaccines. Full article

Climate-change-induced drought threatens forest restoration by limiting seedling establishment. To address this, we developed synthetic bacterial communities (SynComs) tailored to support drought tolerance in two Mediterranean tree species, Quercus pubescens and Sorbus domestica. Bacteria were isolated from forest soil exposed to long-term drought, sampling across soil depths and root-associated compartments. We selected strains with key plant-beneficial traits, including exopolysaccharide (EPS) production, hormone synthesis (auxin, ABA), siderophore release, and osmotic tolerance. SynComs were assembled based on functional complementarity and ecological origin. Biofilm assays showed that even weak individual producers could enhance community-level performance. After initial screening on Arabidopsis thaliana, the most and least effective SynComs were tested on Q. pubescens and S. domestica seedlings. Compared to controls, the best-performing SynComs reduced the proportion of drought-symptomatic seedlings by 47% in Q. pubescens and 71% in S. domestica, outperforming single-strain inoculants. Notably, EPS-rich SynCom B aligned with the conservative root traits of Q. pubescens, while hormone-rich SynCom F matched the acquisitive strategy of S. domestica. Predictive modeling identified bacterial identity and symptom timing as key predictors of drought resilience. Our results highlight the value of matching microbial traits with plant strategies and drought context for climate-smart forest restoration. Full article

Microbially synthesized postbiotics have unique properties and advantages; however, systematic studies on the efficient production and biological functions of postbiotics from Bacillus subtilis are limited, which greatly restricts their applications. In this study, we obtained a novel crude exopolysaccharide (EPS) postbiotic from Bacillus subtilis H4. We systematically optimized the EPS production strategy using single-factor analysis, Plackett–Burman design, the path of steepest ascent method, and response surface methodology. The optimized EPS yield was significantly improved, with a maximum yield of 15.01 g/L under the addition of 4.12% soy peptone, 8.99% sucrose, and 0.06% MnSO₄. We found that EPS is a neutral, heterogeneous polysaccharide with a pyranose ring, with a molecular weight of 44,304.913 kDa and a melting point of 218 °C. It consists of glucose, galactose, arabinose, glucosamine, and mannose at a molar ratio of 58.85:19.81:14.75:10.89:6.58. EPS exhibits strong antioxidant capacities, scavenging ABTS and DPPH radicals with IC50 values of 1 and 6 mg/mL, respectively. Moreover, it shows notable anti-inflammatory properties, dramatically inhibiting the lipopolysaccharide (LPS)-induced elevation of nitric oxide (NO) levels and over-activation of the TLR4-NF-κB signaling pathway. These findings highlight the potential of EPS as a multifunctional bioactive compound, offering great promise for its application in the food, clinical, and feed industries. Full article

Lacticaseibacillus (L.) rhamnosus CRL75 is a lactic acid bacterium (LAB) isolated from local dairy products, demonstrating significant adaptation in skimmed milk (FM75). In this context, CRL75 exhibited high microbial growth (3.63 ± 0.18 log CFU·mL⁻¹), strong acidification (9.20 ± 0.10 g·L⁻¹ lactic acid, and 2.40 ± 0.10 pH units), and increased viscosity in FM75 after 16 h of fermentation. Additionally, this LAB strain produces both capsular polysaccharides (CPS+) and extracellular polysaccharides (EPS75), contributing to a ropy phenotype (>10 cm). The purified EPS75 (70.70 ± 3.25 mg·L⁻¹) displayed low molecular weight (12.7 kDa), with galactose and glucose as its primary monomers in a 4:1 ratio. In aqueous environments, EPS75 exhibited an extended size (147 nm), a random coil structure, and macromolecular aggregation. Furthermore, vibrational spectroscopy confirmed the presence of a neutral EPS with high thermal stability. Additionally, EPS75 exhibited dose-dependent antioxidant activity, effectively reducing metal ions (Fe³⁺, Mo⁶⁺, and Mn⁷⁺) and stabilizing radicals (ABTS^•+, HO^•, O₂^•−, and HOO^•). The biopolymer also demonstrated immunostimulatory and anti-inflammatory effects in RAW 264.7 cells. In vivo assays using Balb/c mice indicated that both EPS75 and FM75 prevented constipation, suggesting their potential as natural and safe agents for constipation-related disorders. Due to its viscosifying and health-promoting attributes, CRL75 offers promising applications for functional dairy products. Full article