Activity Of Exopolysaccharide Research Articles

New insight into protective effect against oxidative stress and biosynthesis of exopolysaccharides produced by Lacticaseibacillus paracasei NC4 from fermented eggplant.

Fermented eggplant is a traditional fermented food, however lactic acid bacteria capable of producing exopolysaccharide (EPS) have not yet been exploited. The present study focused on the production and protective effects against oxidative stress of an EPS produced by Lacticaseibacillus paracasei NC4 (NC4-EPS), in addition to deciphering its genomic features and EPS biosynthesis pathway. Among 54 isolates tested, strain NC4 showed the highest EPS yield and antioxidant activity. The maximum EPS production (2.04 ± 0.11g/L) was achieved by culturing in MRS medium containing 60g/L sucrose at 37°C for 48h. Under 2mM H2O2 stress, the survival of a yeast model Saccharomyces cerevisiae treated with 0.4mg/mL NC4-EPS was 2.4-fold better than non-treated cells, which was in agreement with the catalase and superoxide dismutase activities measured from cell lysates. The complete genome of NC4 composed of a circular chromosome of 2,888,896bp and 3 circular plasmids. The NC4 genome comprises more genes with annotated function in nitrogen metabolism, phosphorus metabolism, cell division and cell cycle, and iron acquisition and metabolism as compared to other reported L. paracasei. Of note, the eps gene cluster is not conserved across L. paracasei. Pathways of sugar metabolism for EPS biosynthesis were proposed for the first time, in which gdp pathway only present in few plant-derived bacteria was identified. These findings shed new light on the cell-protective activity and biosynthesis of EPS produced by L. paracasei, paving the way for future efforts to enhance yield and tailor-made EPS production for food and pharmaceutical industries.

A New Approach to Exopolysaccharides of Post Probiotic Lactobacillus paracasei L1 Strain: Anti-quarum Sensing Activity

Multi-antibiotic resistance, which has increased in recent years, poses a serious societal threat as it makes the fight against deadly infection-causing pathogens even more complex and difficult. As such, the search for naturally resistant probiotic microorganisms and metabolic products obtained from these organisms to prevent infections, as an alternative to antibiotics, is crucial. In this context, preventing the quorum sensing (QS) mechanism that provides communication among bacteria is considered a mechanism that can prevent the colonization and progression of deadly infections. To determine the QS mechanism and the immunological effects and various biological and biochemical characterizations of exopolysaccharide (EPS) obtained from the Lactobacillus paracasei L1 strain isolated from the vaginal microflora of healthy women. Experimental laboratory study. The antibacterial ability, the antibiofilm and QS forming activities, and interferon (IFN)-γ and interleukin (IL)-10 production capacities of EPS were determined. The total antioxidant capacity (TAC), the surface morphology of EPS by scanning electron microscopy (SEM), the presence of functional groups, and the monosaccharide composition were determined by gas chromatographymass spectrometry (GC-MS). L. paracasei L1-EPS demonstrated a strong antibiofilm activity on Escherichia coli (65.14%), Staphylococcus aureus (63.27%), and Pseudomonas aeruginosa (54.21%) at a concentration of 5.0 mg/ml. The anti-QS activity of EPS was found to be quite high at 10 mg/ml EPS concentration. In the study performed with human peripheral blood mononuclear cells (hPBMC), the immunostimulatory IFN-γ value was higher (45 ± 0.0.3) than that in the experimental group, while the IL-10 value was lower than that in the control group (36 ± 0.05). The TAC value of L. piracies L1- EPS was found to be 76 μg/ml at 1,000 μg concentration. According to the GC-MS analysis results, glucose constituted 13.80% of the monosaccharide composition of EPS, while alpha-D-galactose constituted 13.89%. Interestingly, EPSs of L. paracasei L1 strain, which have not been reported previously, demonstrated high anti-QS and antibiofilm properties, making EPSs a prospective compound for application in the pharmaceutical and food industries owing to their strong antimicrobial and antioxidant capacities.

Characterization of structure and antioxidant activity of exopolysaccharides from endophytic Lysinibacillus sphaericus Ya6 under acid-base stress

In this study, the structure and antioxidant activity of exopolysaccharides (EPS) produced by Lysinibacillus sphaericus Ya6 under different acid-base stresses were investigated. The structure of EPS was analyzed by UV-visible and mid-IR, and the monosaccharide composition and the molecular weight were determined by High-performance liquid chromatography (HPLC) and high-performance gel permeation chromatography respectively. The findings indicated that EPS produced by Lysinibacillus sphaericus Ya6 was a homogenous polysaccharide with a molecular weight of 79.25 kDa that was composed of mannose and glucose. The molecular weight and monosaccharide composition of polysaccharides changed under acid-base stress conditions. With the addition of the acid-base stress level, the logarithmic growth period of Lysinibacillus sphaericus Ya6 was prolonged for a short while, but later growth rates and EPS production under stress conditions were all higher than under the control. In vitro determinations found that acid-base stress boosted the antioxidant activity of EPS. Particularly under conditions of alkaline stress, DPPH radical scavenging capacity and superoxide anion scavenging of EPS were higher than those of the control, and their capacities to scavenge DPPH was increased from 39.30% (the control) to 95.65% at pH 10.0, which was close to ascorbic acid's (95.77%) as a positive control.

Production of the exopolysaccharide from Lactiplantibacillus plantarum YT013 under different growth conditions: optimum parameters and mathematical analysis

ABSTRACT Exopolysaccharides (EPSs) are highly heterogeneous natural polymers, can exhibit some unique bio-logical activities, such as anti-oxidation, inflammation regulation, anticancer and anti-viral activities, etc. A new type of EPS was obtained from the fermentation supernatant of Lactiplantibacillus plantarum YT013. However, the low yield of EPS posed a challenge for further research and application. Therefore, in this study, the production process of EPS was optimized, and anti-cancer cells proliferation activity was investigated. Identified the best single-factor conditions for EPS production, including initial pH 6, inoculation amount 5% (v/v), temperature 37°C, cultivation time 36 h, glucose 3% (w/v), soy peptone 1.5% (w/v), KH2PO4 0.3% (w/v). Under these conditions, the maximum production of EPS reached 0.630 mg/mL, which is 1.31 times higher than that before optimization. Concurrently, the nonlinear model was used for fitting, and it was found that the Voigt nonlinear model was in better agreement with the optimization results, which can be used as an effective tool for optimizing EPS production conditions. Furthermore, the anti-proliferative activity of EPS was evaluated using the human gastric cancer AGS cell line in vitro. MTT assay revealed a strong inhibitory effect of EPS on AGS cell proliferation. Additionally, flow cytometry analysis indicated that EPS promoted apoptosis in AGS cells. Lactiplantibacillus plantarum YT013 EPS, as a biodegradable and nontoxic natural active substance, shows potential as a natural antitumor substance.

Exopolysaccharide from Rhodococcus pyridinivorans ZZ47 Strain: Evaluation of Biological Activity and Toxicity

Microbial polysaccharides are extracellular polymeric macromolecules excreted in microorganisms. These are widely used in food, cosmetic and pharmaceutical industries. One of them, exopolysaccharides (EPS), plays important role against the factors such as phage attack, antibiotics, toxic compounds or osmotic stress. Recently, this natural polymer has received great attention due to their therapeutic potential. The purpose of the study was to evaluate biological activity and potential toxicity of EPS from Rhodococcus pyridinivorans ZZ47 strain isolated from nature. EPS has no genotoxic effect on Salmonella typhimurium TA98, TA102, and TA1537 strains by Ames Test. No death occurred with single dose oral toxicity test of EPS and LD50 value of it is calculated by >2000 mg/kg in mice. The EPS showed antibiofilm activity on different bacteria. In addition, EPS demonstrated dose-dependent anti-angiogenic properties by HET-CAM test. In conclusion, the isolated EPS has antioxidant activity with no genotoxicity and the biological activities of the polymer indicated that it may be suitable for use in different sectors and industrial applications.

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.

Isolation, Identification, and Characterization of Tetrodotoxin Producing Bacillus amyloliquefaciens B1 Originated from Carcinoscorpius rotundicauda

This study isolated and identified Bacillus amyloliquefaciens B1 from Carcinoscorpius rotundicauda by carrying out the 16S rRNA sequence analysis, reconstructing the phylogenetic tree based on the Environment for Tree Exploration (ETE3) v3.1.1 belonging to the GenomeNet. By an indirect competitive enzyme-labeled immunoassay, B1 could produce tetrodotoxin (TTX) in MRS was more highly than LB media. After purification, TTX producing ability in B1 could be detected in ELISA assay, high performance liquid chromatography (HPLC). The gel permeation chromatography and gas chromatography were applied to determine the molecular weight of EPS and the concentration of glucose in EPS. The results indicated the highest molecular weight of exopolysaccharides (EPS) estimated 1.33 × 106 Da consisted of glucose (150.09 µg/g). TTX yield was proportional to EPS production in the bacterium. The antimicrobial activities of EPS were determined by agar well diffusion method. Diameter of inhibition zone (mm) of Bacillus amyloliquefaciens EPS on the test microorganisms. The EPS could inhibit against Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Vibrio parahaemolyticus ATCC 17802 and Micrococcus luteus ATCC 10240. In silico prediction, TTX might interact with Bacillus amyloliquefaciens via the extracellular domain of noncanonic ABC-type transporter from gram positive bacteria. TTX might also interact with peptidase S54, mistic, metal binding protein of Bacillus subtilis and tryptophan-rich sensory protein of Bacillus cereus. This study provides the understanding of TTX producing Bacillus amyloliquefaciens B1 isolated from Carcinoscorpius rotundicauda.

Evaluation of antioxidation, regulation of glycolipid metabolism and potential as food additives of exopolysaccharide from Sporidiobolus pararoseus PFY-Z1

At present, there are relatively few studies on the production of exopolysaccharide (EPS) by yeasts. Therefore, exploring the properties of EPS produced by yeast can not only enrich the source of EPS, but also play an important role in its future application in the food field. The aim of this study was to explore the biological activities of EPS (named SPZ) from Sporidiobolus pararoseus PFY-Z1, as well as the dynamic changes in physical and chemical properties that occur during simulated gastrointestinal digestion, and the effects of SPZ on microbial metabolites during fecal fermentation in vitro. The results revealed that SPZ had good water solubility index, water-holding capacity, emulsifying ability, coagulated skim milk, antioxidant properties, hypoglycemic activities, and bile acid-binding abilities. Furthermore, the content of reducing sugars increased from 1.20 ± 0.03 to 3.34 ± 0.11 mg/mL after gastrointestinal digestion, and had little effect on antioxidant activities. Moreover, SPZ could promote the production of short-chain fatty acids during fermentation for 48 h, in particular, propionic acid and n-butyric acid increased to 1.89 ± 0.08 and 0.82 ± 0.04 mmol/L, respectively. Besides this, SPZ could inhibit LPS production. In general, this study can help us to better understand the potential bioactivities, and the changes in bio-activities of compounds after digestion of SPZ.

Protective effect of Paecilomyces cicadae TJJ11213 exopolysaccharide on intestinal mucosa and regulation of gut microbiota in immunosuppressed mice

The exopolysaccharide (EPS) form Paecilomyces cicadae TJJ1213 possessed immunomodulatory activity in vitro, but whether it could regulate the immune system and intestinal microbiota in vivo remained unknown. In this study, the cyclophosphamide (CTX)-induced immunosuppressive mouse model was established to explore the immunomodulatory activity of EPS. Results showed that EPS could increase the immune organ indices, promote the secretion of serum immunoglobulins and up-regulate the expression of cytokines. Additionally, EPS could repair CTX-induced intestinal injury by increasing the expression of tight junction proteins and promoting the production of short-chain fatty acids. Moreover, EPS could remarkably enhance immunity through TLR4/MyD88/NF-κB and mitogen-activated protein kinase (MAPK) signaling pathways. Furthermore, EPS regulated intestinal microbiota by increasing the abundance of beneficial bacteria (Muribaculaceae, Lachnospiraceae NK4A136, Bacteroides, Odoribacter) and reducing the level of harmful bacteria (Alistipes, Helicobacter). In conclusion, our study suggested that EPS had the abilities to enhance immunity, restore intestinal mucosal injury and modulate intestinal microbiota, and may serve as a potential prebiotic to maintain health in the future.

Effect of salinity on the biochemical characteristics and antioxidant activity of exopolysaccharide of Porphyridium purpureum FACHB 806

Porphyridium exopolysaccharide (EPS) is a kind of high-value biopolymer with various biological activities secreted by microalgae belonging to Porphyridium genus. Salinity is one of the important environmental factors affecting the growth of microalgae. In order to study the effect of salinity, the yield, biochemical characteristics and antioxidant activity of EPS in Porphyridium purpureum FACHB 806 cultured at four salinity levels (5‰, 20‰, 35‰ and 50‰) were investigated in this study. The results demonstrated that P. purpureum FACHB 806 could grow at all salinity levels. The highest cell density and EPS yield per cell were 6.6 × 107 cells·mL-1 and 29.1 pg·cell-1, which were obtained in the 20‰ and 50‰ salinity, respectively. With the increase of salinity, the percentage of xylose and galactose decreased while the percentage of glucose increased. Among all salinity levels, the 5‰ salinity group achieved the maximum contents of total carbohydrate and uronic acid of EPS, and the 50‰ salinity obtained the highest protein content of EPS. Compared to the 20‰ and 35‰ salinity groups, EPS of the 5‰ and 50‰ salinity showed stronger hydroxyl radical scavenging ability. These results indicated that salinity could influence the yield, biochemical composition and antioxidant activity of EPS, which will provide a new strategy to improve the yield and antioxidant activity of EPS.

Characterization of exopolysaccharide produced by probiotic Enterococcus durans DU1 and evaluation of its anti-biofilm activity.

Exopolysaccharides (EPS) produced by lactic acid bacteria are complicated polymers with industrial applications. LAB were isolated, screened for EPS production, and their probiotic properties determined. The anti-biofilm activity of EPS was investigated. Safety of EPS-producing isolate was investigated and it was molecularly identified through 16S rRNA sequencing. Finally, anti-biofilm and emulsification activity of EPS was studied and it was characterized using FT-IR, TGA, 1H-NMR, DLS and HPLC. Thirteen LAB were isolated from dairy products. They showed probiotic characteristics like acid resistance (0-6.51CFUml-1) hydrophobicity (8-54.04%), autoaggregation (0% [t = 2h]-99.8% [t = 24h]) and coaggregation with food borne pathogens. Among them, Enterococcus durans DU1 had ability to produce EPS. EPS of Enterococcus durans DU1 showed antibiofilm activity against Y. enterocolitica (24.06-51.36%), S. aureus (12.33-49.6%), and B. cereus (11.66-27.16%). FT-IR showed this EPS had characteristic absorption peaks due to the presence of the pyran ring of sugars. 1H NMR showed that EPS has N-acetyl, methyl, and alkyl groups in its structure. The HPLC analysis showed that EPS is a heteropolysaccharide and consists of sucrose, glucose, and fructose. EPS showed significant thermal stability (20% weight loss) under 300°C and zeta potential of -18.1mV. This EPS can be used in the food industry with no adverse effect on consumers.

Evaluation of Biological Activities of Exopolysaccharide from Rhodococcus pyridinivorans In vitro

Microbial exopolysaccharides (EPSs) are biopolymers in the form of carbohydrates produced by many microorganisms and secreted into the external environment. EPS protects the microorganism from drying, phagocytosis, and phage effects, and acts as a barrier in stress environments such as heat, light and sound. EPSs produced for industrial purposes are generally used in areas such as food, cosmetics, petroleum and chemistry. This study was aimed to investigate in addition to basic physical and chemical properties of R. pyridinovorans EPS, in vitro its biological activities such as antioxidant properties and antiproliferative activity. The antioxidant properties of EPS were determined by DPPH and hydroxyl radical elimination. The antiproliferative activity of EPS on HT-29 and MCF-7 cell lines was determined by MTT assay. The results of study indicate that EPS from R. pyridinovorans have important biological activities. Further studies on structural and mechanism elucidation of the bacterial EPSs are still needed being carried out.

Influence of carbon and nitrogen sources on structural features and immunomodulatory activity of exopolysaccharides from Ganoderma lucidum

In this work, the effects of various carbon and nitrogen sources on structural features and immunomodulatory activity of exopolysaccharides (EPS) from Ganoderma lucidum were studied. When glucose and yeast powder were used as carbon and nitrogen sources, the apparent viscosity of fermentation broth and EPS yield and the corresponding sugar content were higher than those cultured with other carbon and nitrogen sources. The main polysaccharide components (20E) with molecular weights ranging from 2.78 × 106 to 3.96 × 106 g/mol were isolated from fermentation broth through 20% ethanol precipitation. Monosaccharide analysis showed that the carbon source significantly affected the monosaccharide compositions of 20E, and the initial carbon source of the medium accounted for the largest proportion of monosaccharide in 20E. The immunoenhancing activities on inducing NF-κB activation by 20E fractions from different carbon and nitrogen combinations exhibited significant differences. Correlation analysis demonstrated that the immunomodulatory activity of 20E fractions was positively correlated with sugar contents and the molar ratios of glucose, while it was negatively correlated with the molar ratios of xylose. As the structural features and biological activities of EPS are highly dependent on the polysaccharide medium composition, this variability can be used advantageously to produce tailor-made polysaccharides with specific applications.

Exopolysaccharides production from marine Bacillus strains and their antioxidant and bio-flocculant capacities.

Microbial exopolysaccharides (EPS) have gained high scientific concern due to their exceptional physicochemical features and high industrial applicability. Owing to their biotechnological importance, the present study was designed to screen and isolate the EPS-producing Bacillus strains based on their growth potential on specific media and colony morphologies. The bacterial isolates Bacillus subtilis Bs1-01, Bacillus licheniformis Bl1-02, and Bacillus brevis Bb1-04 showed excellent EPS production due to their shortened lag phase and abundant biomass production. Shake-flask fermentation valued the maximum production yield of 50.19 ± 1.14g/L by Bl1-02 after 72h incubation (about 3.40 times higher than that of Bacillus thuringiensis Bt1-05). The basic component analysis revealed the improved amount of total carbohydrate, reducing sugar ends, and protein contents by Bl1-02 strain. Structural characteristics and functional groups of the EPS characterized by Fourier transform infrared spectroscopy demonstrated that all EPS were in close agreement to each other due to the presence of similar chemical bonds and functional groups. EPS from Bl1-02 strain showed stronger and more stable bio-emulsifying and hygroscopicity activities (12.23%). The crude EPS exhibited potent antioxidant properties which were examined against reducing potential (H2O2 scavenging) and total antioxidant tests. Among bio-flocculation activities of EPS at different concentrations, Bs1-01 strain produced EPS at a concentration of 60mg/mL was observed to show the maximum value of 79.20%. In conclusion, the EPS from marine Bacillus strains showed excellent functional properties suggesting potential industrial applications that demand separate investigations.

Evaluation of anti-tumor effect of the exopolysaccharide from new cold-adapted yeast, Rhodotorula mucilaginosa sp. GUMS16 on chronic myeloid leukemia K562 cell line

Recently, the development and application of fungal exopolysaccharides (EPS) as natural biopolymers are on the rise. The present study is based on the investigation of possible antiproliferative and antioxidant activities of EPS from the Rhodotorula mucilaginosa sp. GUMS16 on BCR-ABL positive cells (K562). The cytotoxicity, colony formation assays lactate and dehydrogenase (LDH) activity were performed to assess the possible cancer cell death. To elucidate the underlying antiproliferative mechanism of the EPS, cell cycle analysis following real-time PCR (gene expression assessment) were evaluated. The results indicated that, the EPS with an IC50 dose of 1500 μg/ml, reduced the viability of K562 cells without having toxic effects on normal cells as well as decrease in size and number of colonies in EPS-treated group (p < 0.0001). The increase of LDH was 2.75 times more than the control (p < 0.0001). Gene expression revealed up- and down-regulation of apoptotic and anti-apoptotic genes in EPS group compared with the control. Moreover, the DPPH scavenging activity of the EPS in treated cells was significantly higher than the control group (p < 0.0001). Taken together, we concluded that the EPS from GUMS16 strain is able to inhibit the growth of K562 cells besides having antioxidant activities.

Role of genistein on the yield, structure and immunomodulatory activity of Monascus exopolysaccharides.

Manipulating the structures, physicochemical properties, and monosaccharide compositions of exopolysaccharides (EPS) isolated from microorganisms has been reported to enhance their biological activities. Hence, the aim of this work was to examine the effects of genistein addition during fermentation on the amount, physicochemical properties, and immunomodulatory activity of EPS secreted by M. purpureus. Results showed that genistein addition significantly increased M. purpureus biomass and EPS yield to 2.42 g L-1 and 6.08 g L-1, respectively, and affected the physicochemical properties and structures of EPS. Furthermore, EPS produced by genistein-treated M. purpureus (G-EMP) improved the immunomodulatory activity of RAW264.7 macrophages by increasing the secretion of nitric oxide and cytokines. Moreover, phospho-Jun N-terminal kinase (p-JNK), phospho-extracellular regulated protein kinase (p-ERK), phospho-p38 (p-p38) mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) phospho-p65 (p65) proteins were remarkably upregulated by G-EMP stimulation, blocking Toll-like receptor 4 (TLR4) that dramatically reduced the pinocytic and phagocytic capacities. Overall, these findings provide potential rationales for the application of genistein in improving the EPS yield of M. purpureus.

Exopolysaccharides from Klebsiella oxytoca: anti-inflammatory activity

Exopolysaccharides (EPS) produced by Klebsiella oxytoca are of environmental, pharmaceutical, and medicinal interest. However, studies about the anti-inflammatory activity of EPS produced by this microorganism still remain limited. The aim of this study was to produce, characterize, and evaluate the anti-inflammatory activity of EPS from K. oxytoca in a pleurisy model. Colorimetric analysis revealed that precipitated crude exopolysaccharides (KEPSC) and deproteinated exopolysaccharides (KEPS) present high levels of total carbohydrates (65.57% and 62.82%, respectively). Analyses of uronic acid (7.90% in KEPSC and 6.21% in KEPS) and pyruvic acid (3.01% in KEPSC and 1.68% in KEPS) confirm that the EPS are acidic. Gas chromatography-mass spectrometry analyses demonstrated that the EPS consisted of rhamnose (29.83%), glucose (11.21%), galactose (52.45%), and mannose (6.50%). The treatment of an experimental pleurisy model in rats through subcutaneous administration of 50, 100, 200, and 400 mg/kg of KEPS decreased both the volume of inflammatory exudate and the number of leukocytes recruited to the pleural cavity. The present data showed that EPS production by K. oxytoca using the method described is easy to perform and results in a good yield. In addition, we show that KEPS exhibit anti-inflammatory activity when administered subcutaneously in rats.

Characterization of antioxidant activity of exopolysaccharides from endophytic Lysinibacillus sphaericus Ya6 under osmotic stress conditions

In this study, the antioxidant properties of exopolysaccharides (EPS) produced by Lysinibacillus sphaericus Ya6 under different osmotic stress were investigated. High-performance liquid chromatography was used to analyse the monosaccharide composition of EPS. High-performance gel permeation chromatography was used to determine the molecular weight of EPS. Results suggested that EPS produced by Lysinibacillus sphaericus Ya6 was a homogenous polysaccharide with molecular weight of 89.62 kDa, which was composed of mannose and glucose. The molecular weight and monosaccharide composition of polysaccharides changed under osmotic stress conditions. In vitro antioxidant determinations found that all EPS had activity of scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and superoxide anion. And with the aggravation of osmotic stress, the scavenging activity of EPS produced by Lysinibacillus sphaericus Ya6 on DPPH radical was enhanced from 39.30 ± 0.19 % (control condition) to 72.54 ± 0.3 %.

Exopolysaccharides as Antimicrobial Agents: Mechanism and Spectrum of Activity.

Exopolysaccharides (EPSs) are metabolites synthesized and excreted by a variety of microorganisms, including lactic acid bacteria (LAB). EPS serve several biological functions such as interactions between bacteria and their environments, protection against hostile conditions including dehydration, the alleviation of the action of toxic compounds (bile salts, hydrolyzing enzymes, lysozyme, gastric, and pancreatic enzymes, metal ions, antibiotics), and stresses (changing pH, osmolarity), and evasion of the immune response and phage attack. Bacterial EPSs are considered valuable by the food, pharmaceutical, and nutraceutical industries, owing to their health-promoting benefits and rheological impacts. Numerous studies have reported the unusual antimicrobial activities of various EPS against a wide variety of pathogenic microbes (bacteria, virus, and fungi). This review aims to provide a comprehensive examination of the in vitro and in vivo antimicrobial activities of different EPSs, mainly against foodborne bacterial, fungal, and viral pathogens. The mechanism of EPS action against these pathogens as well as the methods used to measure antimicrobial activities are critically reviewed.

Optimization and characterization of exopolysaccharide produced by Bacillus aerophilus rk1 and its in vitro antioxidant activities

ObjectiveIn this study, the isolation and identification of Exopolysaccharide (EPS) producing bacteria from polluted soil samples and its in vitro antioxidant activities were investigated. MethodsIsolation and identification of bacteria was investigating using 16 s rDNA genome sequencing method. Further, optimization (pH, time, and temperature), purification and characterization of EPS were performed using different (UV, FT-IR, C13-NMR and H1-NMR) methods. In addition, 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide (H2O2) scavenging activities of EPS were performed. ResultsThe molecular characterization of isolated strain was confirmed as Bacillus aerophilus by 16S rDNA sequencing. The sequence was submitted to NCBI (Genbank accession number MH553072). Characterization of EPS by UV, FT-IR, C13-NMR and H1-NMR revealed the presence of hydroxyl, carbonyl, and carboxyl functional groups. SEM analysis of EPS showed a solid surface with an irregular shape. The optimum conditions for EPS production were pH 7.0, cultivation time 72 h (3.73 ± 0.211 g/L) and temperature 30 °C respectively. The yeast and sucrose extract showed higher EPS production. In addition, in vitro DPPH, H2O2 studies showed 56.6 and 67.5% of scavenging activity at 4 mg/mL of concentration. ConclusionsFrom this study, the novel EPS producing Bacillus aerophilus rk1 was identified. Further, the purified EPS showed good antioxidant activity.