Influence Of Exopolysaccharides Research Articles

Influence of exopolysaccharides on viscosity of sugar juices with low sucrose contents

The presence of dextran originating from frost-damaged or degraded beet is highly detrimental during beet sugar manufacture, because they cause difficulties in filtering the carbonatation juice. In this paper the impact of exopolysaccharides on the viscosity of low sucrose content juices including: raw juice, juice after the 1st filtration and thin juice were analyzed. Studies have shown that high molecular mass exopolysaccharides have a stronger effect on the juice viscosity than low molecular mass exopolysaccharides. However, the dynamic viscosity of technical sugar solutions (raw juice or thin juice) with exopolysaccharides at a content of up to 0.5 g/kg, is lower than the viscosity of pure sugar solutions having the same refractometric dry substance content (RDS).

Исследование влияния экзополисахарида на товароведно-технологические характеристики рубленых полуфабрикатов из кур

Исследование влияния экзополисахарида на товароведно-технологические характеристики рубленых полуфабрикатов из кур

Exopolysaccharides Produced by Lactobacillus rhamnosus KL 53A and Lactobacillus casei Fyos Affect Their Adhesion to Enterocytes.

Probiotics promote and help to maintain beneficial microbiota composition of the gastrointestinal tract ecosystem and have a positive impact on the host’s health. Production of exopolysaccharides is an important feature of probiotic lactobacilli. It increases the chance of their survival in the gastrointestinal tract and promotes adhesion to the epithelium; therefore, exopolysaccharides are important for the process of colonization. Two lactic acid bacteria strains were used in this study: Lactobacillus rhamnosus KL 53A and Lactobacillus casei Fyos. Exopolysaccharides were isolated from bacterial cells and their monosaccharide composition was examined using liquid chromatography. The influence of exopolysaccharides on lactobacilli adhesion to enterocytes was studied after deglycosylation of the bacterial cells and incubation with the selected intestinal microbiota strains that metabolize polysaccharides – Faecalibacterium prausnitzii DSM 17677 and Blautia luti DSM 14534. Both deglycosylation and incubation with polysaccharide metabolizing strains influenced the ability of probiotic strains to adhere to enterocytes. Enzymatic deglycosylation decreased adhesion efficiency of L. rhamnosus KL 53A; however, co-incubation of both lactobacillus strains with F. prausnitzii DSM 17677 resulted in an increase of their adhesion efficiency. Exopolysaccharides are important adhesins of Lactobacillus spp. that influence their ability to colonize gut epithelium. Other members of gut microbiota can modify the adhesion property in situ; therefore the composition and metabolic state of commensal bacteria may influence their probiotic action.

Structural and surface properties of whey protein from buffalo milk as influenced by exopolysaccharide

ABSTRACTThe influence of exopolysaccharide (EPS) on the structure of whey protein (WP) molecules at different pH and ionic strengths was investigated using fluorescence and circular dichroism (CD) spectroscopy. The WPs were separated using 0.2 mol/L glacial acetic acid, which has been proved to maintain to the maximum extent the native structure of WP molecules. The interaction between WP and EPS was significantly influenced by the ionic strength and pH. The presence of NaCl reduced the repulsion and aggregation of WP at pH 7.0. The addition of EPS increased the β-sheet structure of WP and this change tends to disappear at high ionic strength (0.3 mol/L). On the other hand, the repulsive interaction between WP and EPS at pH 7.0 and 6.0 has minimal influence on tryptophan (Trp) quenching and the exposure of hydrophobic residues to the hydrophilic environment. The formation of WP/EPS complexes at pH 5.0 led to the increased exposure of the Trp group to the hydrophilic phase. Both the electrostatic repulsion and attraction increased the secondary structure of WP at all pH values tested in this research.

Influence of exopolysaccharides on the electrophoretic properties of the model cyanobacterium Synechocystis

The influence of extracellular polymeric substances (EPS) on cell electrokinetics was investigated in the model cyanobacterium Synechocystis, in wild-type strains and in ten EPS-depleted mutants. The charge density and the softness of the EPS polyelectrolyte layer were calculated from the dependence of the electrophoretic mobility values of the cells with the ionic strength of the surrounding fluid. Electrophoretic mobility data showed that the eleven Synechocystis strains investigated behave as soft particles and cannot be adequately described by classical electrokinetic models of rigid particles. EPS surrounding the cells, especially those released in the growth medium, significantly increased the softness of the cell surface. Furthermore, the anionic nature of EPS resulted in negative surface charge densities, which appeared to be strongly dependent on the composition of the suspending fluid, as documented by a strong reduction of their absolute values in the presence of calcium cations. These finding stresses the importance of the physicochemical properties of EPS and cell surfaces of cyanobacteria, for both cell-to-medium and cell-to-cell communications. In turn, these results emphasize that, whenever possible, natural waters should be used for meaningful ecotoxicological analyses of potential toxics.

Exopolysaccharides produced by Streptococcus mutans glucosyltransferases modulate the establishment of microcolonies within multispecies biofilms.

Streptococcus mutans is a key contributor to the formation of the extracellular polysaccharide (EPS) matrix in dental biofilms. The exopolysaccharides, which are mostly glucans synthesized by streptococcal glucosyltransferases (Gtfs), provide binding sites that promote accumulation of microorganisms on the tooth surface and further establishment of pathogenic biofilms. This study explored (i) the role of S. mutans Gtfs in the development of the EPS matrix and microcolonies in biofilms, (ii) the influence of exopolysaccharides on formation of microcolonies, and (iii) establishment of S. mutans in a multispecies biofilm in vitro using a novel fluorescence labeling technique. Our data show that the ability of S. mutans strains defective in the gtfB gene or the gtfB and gtfC genes to form microcolonies on saliva-coated hydroxyapatite surfaces was markedly disrupted. However, deletion of both gtfB (associated with insoluble glucan synthesis) and gtfC (associated with insoluble and soluble glucan synthesis) is required for the maximum reduction in EPS matrix and biofilm formation. S. mutans grown with sucrose in the presence of Streptococcus oralis and Actinomyces naeslundii steadily formed exopolysaccharides, which allowed the initial clustering of bacterial cells and further development into highly structured microcolonies. Concomitantly, S. mutans became the major species in the mature biofilm. Neither the EPS matrix nor microcolonies were formed in the presence of glucose in the multispecies biofilm. Our data show that GtfB and GtfC are essential for establishment of the EPS matrix, but GtfB appears to be responsible for formation of microcolonies by S. mutans; these Gtf-mediated processes may enhance the competitiveness of S. mutans in the multispecies environment in biofilms on tooth surfaces.

Characterization of functional, biochemical and textural properties of synbiotic low-fat yogurts during refrigerated storage

This study examined the influence of exopolysaccharides (EPS) produced in situ on the viability of Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus and probiotics, the proteolytic and ACE-inhibitory activities, and textural and rheological properties of inulin-containing probiotic yogurt during refrigerated storage. Two types of yogurt were prepared using strains of S. thermophilus not producing EPS (NEPY) and producing EPS (EPY). The yield of crude EPS increased (by 2.4 times) until day 21 of storage. Presence of EPS showed a protective effect on the survival of L. delbrueckii ssp. bulgaricus and Lactobacillus acidophilus but not on S. thermophilus, Lactobacillus casei and Bifidobacterium longum. No changes in post-acidification, lactic acid content or the ACE-inhibition activity of the two types of yogurt were observed. Overall, EPS containing yogurts exhibited higher proteolysis in the presence of inulin and probiotics (0.698 units) than the corresponding control (0.563 units). The storage and loss moduli (Pa), yield stress (Pa), consistency index (Pa s) and thixotrophic behaviour (Pa s −1) of both samples were similar at day 1 and the influence of EPS was observable only after day 7. Such a variation of the effect of EPS on the textural and rheological properties of low-fat yogurt appears to be partially due to the presence of probiotics.

Textural and functional changes in low-fat Mozzarella cheeses in relation to proteolysis and microstructure as influenced by the use of fat replacers, pre-acidification and EPS starter

The influence of exopolysaccharides (EPS), pre-acidification and use of two fat replacers, FR1 and FR2, on the textural and functional characteristics of Mozzarella cheeses were studied. Control cheeses made with EPS producing Streptococcus thermophilus 285 had the lowest moisture (52.84%) and yield while hardness and melt properties of these cheeses improved with storage. Addition of FR1 or FR2 and pre-acidification of milk increased the moisture content in cheeses. All cheeses were softer than the control. Cheeses made with FR1 exhibited the greatest stretch and melt; those made with FR2 showed poor stretch and melt. Each cheese showed a unique microstructure prior to, and after the hydration of the protein matrix. The rate of α - and β -casein proteolysis was greater in cheeses made with pre-acidified milk and those having higher moisture content. Pizza bake performance was improved with FR1, but FR2 cheeses had the least favourable bake characteristics. Coating cheese shreds with oil was necessary for adequate browning, melt and flow.

Attachment and Biofilm Formation by Escherichia coli O157:H7 on Stainless Steel as Influenced by Exopolysaccharide Production, Nutrient Availability, and Temperature

The influence of exopolysaccharide (EPS) production, nutrient availability, and temperature on attachment and biofilm formation by Escherichia coli O157:H7 strains ATCC 43895 (wild type) and 43895-EPS (extensive EPS-producing mutant) on stainless steel coupons (SSCs) was investigated. Cells grown on heated lettuce juice agar and modified tryptic soy agar were suspended in phosphate-buffered saline (PBS). SSCs were immersed in the cell suspension (109 CFU/ml) at 4°C for 24 h. Biofilm formation by cells attached to SSCs as affected by immersing in 10% tryptic soy broth (TSB), lettuce juice broth (LJB), and minimal salts broth (MSB) at 12 and 22°C was studied. A significantly lower number of strain 43895-EPS cells, compared to strain ATCC 43895 cells, attached to SSCs during a 24-h incubation (4°C) period in PBS suspension. Neither strain formed a biofilm on SSCs subsequently immersed in 10% TSB or LJB, but both strains formed biofilms in MSB. Populations of attached cells and planktonic cells of strain ATCC 43895 gradually decreased during incubation for 6 days in LJB at 22°C, but populations of strain 43895-EPS remained constant for 6 days at 22°C, indicating that the EPS-producing mutant, compared to the wild-type strain, has a higher tolerance to the low-nutrient environment presented by LJB. It is concluded that EPS production by E. coli O157:H7 inhibits attachment to SSCs and that reduced nutrient availability enhances biofilm formation. Biofilms formed under conditions favorable for EPS production may protect E. coli O157:H7 against sanitizers used to decontaminate lettuce and produce processing environments. Studies are under way to test this hypothesis.

Technical Note: Influence of Exopolysaccharides on Bacterial Resistance to Ozone

Abstract The influence of polysaccharides on survival of the capsulated K54 A3 and non-capsulated K54 A3 (0) strains of Klebsiella aerogenes exposed to ozone was investigated. Because it had been shown in this work that bacteria lose approximately half of their polysaccharides when suspended in water, all bacterial assays were performed using exactly the same medium surrounding the cells, so as to create the same ozone demand. Sensitivity of both strains A3 and A3(0) to ozone as tested in the laboratory was not significantly different, although the amount of exopolysaccharides adhering to the cells were five-fold greater with A3 than with A3(0).