Structure characterization, antioxidant capacity, rheological characteristics and expression of biosynthetic genes of exopolysaccharides produced by Lactococcus lactis subsp. lactis IMAU11823

Insight into antioxidant and anti-inflammatory effects of marine bacterial natural exopolysaccharide (EPSSM) using carrageenan-induced paw edema in rats

Inflammation is a part of the body's intricate biological reaction to noxious stimuli and defensive reactions. So, the aim of this investigation was to study the anti-inflammatory activity of exopolysaccharide (EPSSM) using carrageenan-induced paw edema in rats. A halophilic bacterial strain was isolated from marine sediments in the Red Sea in Egypt. The isolate has been visually and physiologically recognized, as well as by analyzing its 16S rRNA gene, which confirms Kocuria sp. clone Asker4. This particular isolate can be referenced using the accession number OL798051.1. EPSSM was subjected to purification and fractionation by a DEAE-cellulose column. Preliminary chemical analysis of EPSSM indicated that the monosaccharides were fructose, glucuronic acid, and xylose, with 2.0, 0.5, and 1.0, respectively. The antioxidant potential of EPSSM was investigated, and it was discovered that the level of activity increased independently of the concentrations, reaching a maximum threshold of 94.13% at 100 µg/mL of EPSSM for 120 min. Also, EPSSM at 50 mg/kg orally produced a significant anti-inflammatory effect on the carrageenan model at 2, 3, and 4 intervals. The EPSSM intervention resulted in reductions in the levels of catalase and superoxide dismutase enzymes, as well as a decrease in glutathione. Furthermore, the levels of nitric oxide, lipid peroxidation, and reactive oxygen species resulting from carrageenan-induced edema showed a significant reduction subsequent to the administration of EPSSM. Moreover, the findings indicated that the protein expression levels of cyclooxygenase-2 and interleukin-6 were reduced following treatment with EPSSM, resulting in a reduction of paw edema.

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

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

Structures and diversities of bacterial communities in oil-contaminated soil at shale gas well site assessed by high-throughput sequencing

Currently, there is limited understanding of the structures and variabilities of bacterial communities in oil-contaminated soil within shale gas development. The Changning shale gas well site in Sichuan province was focused, and high-throughput sequencing was used to investigate the structures of bacterial communities and functions of bacteria in soil with different degrees of oil pollution. Furthermore, the influences of the environmental factors including pH, moisture content, organic matter, total nitrogen, total phosphorus, oil, and the biological toxicity of the soil on the structures of bacterial communities were analyzed. The results revealed that Proteobacteria and Firmicutes predominated in the oil-contaminated soil. α-Proteobacteria and γ-Proteobacteria were the main classes under the Proteobacteria phylum. Bacilli was the main class in the Firmicutes phylum. Notably, more bacteria were only found in CN-5 which was the soil near the storage pond for abandoned drilling mud, including Marinobacter, Balneola, Novispirillum, Castellaniella, and Alishewanella. These bacteria exhibited resilience to higher toxicity and demonstrated proficiency in oil degradation. The functions including carbohydrate transport and metabolism, energy metabolism, replication, recombination and repair replication, signal transduction mechanisms, and amino acid transport and metabolism responded differently to varying concentrations of oil. The disparities in bacterial genus composition across samples stemmed from a complex play of pH, moisture content, organic matter, total nitrogen, total phosphorus, oil concentration, and biological toxicity. Notably, bacterial richness correlated positively with moisture content, while bacterial diversity showed a significant positive correlation with pH. Acidobacteria exhibited a significant positive correlation with moisture content. Litorivivens and Luteimonas displayed a significant negative correlation with pH, while Rhizobium exhibited a significant negative correlation with moisture content. Pseudomonas, Proteiniphilum, and Halomonas exhibited positive correlations not only with organic matter but also with oil concentration. Total nitrogen exhibited a significant positive correlation with Taonella and Sideroxydans. On the other hand, total phosphorus showed a significant negative correlation with Sphingomonas. Furthermore, Sphingomonas, Gp6, and Ramlibacter displayed significant negative correlations with biological toxicity. The differential functions exhibited no significant correlation with environmental factors but displayed a significant positive correlation with the Proteobacteria phylum. Aridibacter demonstrated a significant positive correlation with cell motility and cellular processes and signaling. Conversely, Pseudomonas, Proteiniphilum, and Halomonas were negatively correlated with differential functions, particularly in amino acid metabolism, carbohydrate metabolism, and membrane transport. Compared with previous research, more factors were considered in this research when studying structural changes in bacterial communities, such as physicochemical properties and biological toxicity of soil. In addition, the correlations of differential functions of communities with environmental factors, bacterial phyla, and genera were investigated.

A novel exopolysaccharide from Weissella cibaria FAFU821: Structural characterization and cryoprotective activity

Exopolysaccharides produced by Weissella cibaria has attracted increasing attention owing to their biological activity. Here, a strain was isolated from the home-made fermented octopus, which was identified as W. cibaria FAFU821. In addition, the polysaccharide were isolated and purified by cellulose DE-52 column and Sephadex G-100 column, and named EPS821-1. In this work, the structure of EPS821-1 and its cryoprotective activity on Bifidobacterium longum subsp. longum F2 were investigated in vitro. These results suggested that the EPS821-1 is a novel glucan, which mainly consists of α-(1 → 6) linkage with α-(1 → 4), α-(1 → 4,6) and α-(1 → 3,6) residue as branches. In addition, EPS821-1 existed the three-dimensional network structure and exhibited the excellent cryoprotective activities for B. longum subsp. longum F2, which was 2.75 folds higher than that of the controls. This study provided scientific evidence and insights for the application of EPS821-1 as cryoprotection in food field.

Structural characterization, biofunctionality, and environmental factors impacting rheological properties of exopolysaccharide produced by probiotic Lactococcus lactis C15

Exopolysaccharides (EPSs) possess distinctive rheological and physicochemical properties and innovative functionality. This study aimed to investigate the physicochemical, bioactive, and rheological properties of an EPS secreted by Lactococcus lactis subsp. lactis C15. EPS-C15 was found to have an average molecular weight of 8.8 × 105 Da and was identified as a hetero-EPS composed of arabinose, xylose, mannose, and glucose with a molar ratio of 2.0:2.7:1.0:21.3, respectively. The particle size and zeta potential represented 311.2 nm and - 12.44 mV, respectively. FITR exhibited that EPS-C15 possessed a typical polysaccharide structure. NMR displayed that EPS-C15 structure is → 3)α-d-Glcvi (1 → 3)α-d-Xylv (1 → 6)α-d-Glciv(1 → 4)α-d-Glc(1 → 3)β-d-Man(1 → 2)α-d-Glci(1 → . EPS-C15 scavenged DPPH and ABTS free radicals with 50.3% and 46.4% capacities, respectively. Results show that the antiproliferative activities of EPS-C15 revealed inhibitions of 49.7% and 88.1% against MCF-7 and Caco-2 cells, respectively. EPS-C15 has antibacterial properties that inhibited Staphylococcus aureus (29.45%), Salmonella typhimurium (29.83%), Listeria monocytogenes (30.33%), and E. coli O157:H7 (33.57%). The viscosity of EPS-C15 decreased as the shear rate increased. The rheological properties of the EPS-C15 were affected by changes in pH levels and the addition of salts. EPS-C15 is a promising biomaterial that has potential applications in various industries, such as food, pharmaceuticals, and healthcare.

Genome Analysis of Bifidobacterium Bifidum E3, Structural Characteristics, and Antioxidant Properties of Exopolysaccharides

In this study, the antioxidant properties of intact cells (IC), cell-free supernatant (CFS), and cell-free extracts (CFE) and whole genome sequencing of Bifidobacterium bifidum E3 (B. bifidum E3), as well as the structural characteristics and antioxidant properties of EPS-1, EPS-2, and EPS-3, were evaluated. The results revealed that intact cells (IC), cell-free supernatant (CFS), and cell-free extracts (CFE) had potent DPPH (1,1-Diphenyl-2-picrylhydrazyl radical), hydroxyl, and superoxide anion radical scavenging capacities, among which CFS was the best. At the genetic level, we identified a strong carbohydrate metabolism capacity, an EPS synthesis gene cluster, and five sugar nucleotides in B. bifidum E3. Therefore, we extracted cEPS from B. bifidum E3 and purified it to obtain EPS-1, EPS-2, and EPS-3. EPS-1, EPS-2, and EPS-3 were heteropolysaccharides with an average molecular weight of 4.15 × 104 Da, 3.67 × 104 Da, and 5.89 × 104 Da, respectively. The EPS-1 and EPS-2 are mainly comprised of mannose and glucose, and the EPS-3 is mainly comprised of rhamnose, mannose, and glucose. The typical characteristic absorption peaks of polysaccharides were shown in Fourier transform infrared spectroscopy (FT-IR spectroscopy). The microstructural study showed a rough surface structure for EPS-1, EPS-2, and EPS-3. Furthermore, EPS-1, EPS-2, and EPS-3 exhibited potent DPPH, hydroxyl, and superoxide anion radical scavenging capacities. Correlation analysis identified that antioxidant capacities may be influenced by various factors, especially molecular weight, chemical compositions, and monosaccharide compositions. In summary, the EPS that was produced by B. bifidum E3 may provide insights into health-promoting benefits in humans.

Purification, characterization and probiotic proliferation effect of exopolysaccharides produced by Lactiplantibacillus plantarum HDC-01 isolated from sauerkraut

In this study, an exopolysaccharide (EPS)-producing strain of Lactiplantibacillus plantarum HDC-01 was isolated from sauerkraut, and the structure, properties and biological activity of the studied EPS were assessed. The molecular weight of the isolated EPS is 2.505 × 10⁶ Da. Fourier transform infrared spectrometry (FT-IR) and nuclear magnetic resonance (NMR) results showed that the EPS was composed of glucose/glucopyranose subunits linked by an α-(1 → 6) glycosidic bond and contained an α-(1 → 3) branching structure. X-ray diffraction (XRD) analysis revealed the amorphous nature of the EPS. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that the isolated EPS had a smooth and compact surface with several protrusions of varying lengths and irregularly shaped material. Moreover, the studied EPS showed good thermal stability, water holding capacity, and milk coagulation ability and promoted the growth of probiotics. L. plantarum EPS may be used as prebiotics in the fields of food and medicine.

Relationship of Gene-Structure-Antioxidant Ability of Exopolysaccharides Derived from Lactic Acid Bacteria: A Review

Polysaccharides derived from lactic acid bacteria (LAB) have widespread industrial applications owing to their excellent safety profile and numerous biological properties. The antioxidant activity of exopolysaccharides (EPS) offers defense against disease conditions caused by oxidative stress. Several genes and gene clusters are involved in the biosynthesis of EPS and the determination of their structures, which play an important role in modulating their antioxidant ability. Under conditions of oxidative stress, EPS are involved in the activation of the nonenzyme (Keap1-Nrf2-ARE) response pathway and enzyme antioxidant system. The antioxidant activity of EPS is further enhanced by the targeted alteration of their structures, as well as by chemical methods. Enzymatic modification is the most commonly used method, though physical and biomolecular methods are also frequently used. A detailed summary of the biosynthetic processes, antioxidant mechanisms, and modifications of LAB-derived EPS is presented in this paper, and their gene-structure-function relationship has also been explored.

In Vitro Probiotic Characterization and Safety Assessment of Lactic Acid Bacteria Isolated from Raw Milk of Japanese-Saanen Goat (Capra hircus)

Two novel probiotic strains of lactic acid bacteria were successfully isolated from the raw milk of dairy Japanese-Saanen goats. Selection criteria for positive candidates were grown on de Man-Rogosa-Sharpe or M17 selective medium at 30, 35, or 42 °C anaerobically, and characterized based on Gram reaction, catalase test, and tolerance to low pH and bile salts. Among the 101 isolated positive candidates, two strains, YM2-1 and YM2-3, were selected and identified as Lacticaseibacillus rhamnosus using 16S rDNA sequence similarity. Culture supernatants of the two strains exhibited antipathogenic activity against Salmonella enterica subsp. enterica serovar. Typhimurium, Shigella sonnei, methicillin-resistant Staphylococcus aureus, methicillin-sensitive Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli O157. The antipathogenic activities were retained to some extent after neutralization, indicating the presence of antipathogenic substances other than organic acids in the culture supernatants. The two strains were sensitive with coincidental minimum inhibition concentrations (indicated in the parentheses hereafter) to ampicillin (0.25 μg/mL), chloramphenicol (4 μg/mL), gentamycin (4 μg/mL), kanamycin (64 μg/mL), streptomycin (16 μg/mL), and tetracycline (4 μg/mL). Furthermore, the two strains were resistant to clindamycin (16 μg/mL) and erythromycin (4 μg/mL). In addition, both YM2-1 and YM2-3 strains showed less unfavorable activities, including bile acid bioconversion, carcinogenic-related enzymes, mucin degradation, plasminogen activation, and hemolysis, than the detection limits of in vitro evaluation methods used in this study. In summary, L. rhamnosus YM2-1 and YM2-3 are highly safe and promising probiotic strains applicable in the dairy industry, and were first isolated from the raw milk of Japanese-Saanen goats.

Potential Applications of an Exopolysaccharide Produced by Bacillus xiamenensis RT6 Isolated from an Acidic Environment

The Bacillus xiamenensis RT6 strain was isolated and identified by morphological, biochemical and molecular tests from an extreme acidic environment, Rio Tinto (Huelva). Optimisation tests for exopolysaccharide (EPS) production in different culture media determined that the best medium was a minimal medium with glucose as the only carbon source. The exopolymer (EPS_t) produced by the strain was isolated and characterised using different techniques (GC-MS, HPLC/MSMS, ATR-FTIR, TGA, DSC). The molecular weight of EPS_t was estimated. The results showed that the average molecular weight of EPS_t was approximately 2.71 × 10⁴ Da and was made up of a heteropolysaccharide composed of glucose (60%), mannose (20%) and galactose (20%). The EPS_t showed antioxidant capabilities that significantly improved cell viability. Metal chelation determined that EPS_t could reduce the concentration of transition metals such as iron at the highest concentrations tested. Finally, the emulsification study showed that EPS_t was able to emulsify different natural polysaccharide oils, reaching up to an 80% efficiency (olive and sesame oil), and was a good candidate for the substitution of the most polluting emulsifiers. The EPS_t was found to be suitable for pharmaceutical and industrial applications.

Extraction, Structural Analysis, and Biofunctional Properties of Exopolysaccharide from Lactiplantibacillus pentosus B8 Isolated from Sichuan Pickle

Two novel exopolysaccharides, named LPB8-0 and LPB8-1, were isolated and purified from Lactiplantibacillus pentosus B8. Moreover, their structure and bioactivities were evaluated through chemical and spectral means. The study results demonstrated that LPB8-0 was primarily composed of mannose and glucose and had an average molecular weight of 1.12 × 10⁴ Da, while LPB8-1 was composed of mannose, glucose, and galactose and had an average molecular weight of 1.78 × 10⁵ Da. Their carbohydrate contents were 96.2% ± 1.0% and 99.1% ± 0.5%, respectively. The backbone of LPB8-1 was composed of (1→2)-linked α-D-Manp and (1→6)-linked α-D-Manp. LPB8-0 and LPB8-1 had semicrystalline structures with good thermal stability (308.3 and 311.7 °C, respectively). SEM results displayed that both LPB8-0 and LPB8-1 had irregular thin-slice shapes and spherical body structures. Additionally, an emulsifying ability assay confirmed that LPB8-0 and LPB8-1 had good emulsifying activity against several edible oils, and this activity was retained under acidic, neutral, and high temperature conditions. Furthermore, an antioxidant assay confirmed that LPB8-1 had stronger scavenging activity than LPB8-0. Overall, these results provide a theoretical basis for the potential application of these two novel exopolysaccharides as natural antioxidants and emulsifiers in the food and pharmaceutical industries.