Highest Exopolysaccharides Yield Research Articles

Identification and characterisation of dextran produced by a novel high yielding Weissella cibaria Fiplydextran strain

An exopolysaccharide (EPS)-producing bacterial strain was isolated from fermented soy milk and identified as Weissella cibaria strain Fiplydextran through morphological, biochemical and 16S rDNA sequence analysis. Here, we report the optimisation of cultural conditions for the organism to achieve maximum EPS production, along with its molecular characterisation, functional properties, and prebiotic potential. The exceptionally high EPS yield (0.61 g per g of sucrose) was obtained from the optimised medium (200 g/L of sucrose, 15 g/L of yeast extract) at 30 °C after 48 h. HPAEC-PAD analysis revealed that the EPS is homopolymer of glucose having Mw as 3.23 × 107 Da determined using viscosity method. Methylation analysis and NMR results confirmed the EPS as dextran with α (1 → 6)-linkage (96.5 %) as main chain and α (1 → 3)- as branch chain linkage (3.5 %). Thermogravimetric analysis exhibited higher thermal stability of EPS. The EPS was observed to support the growth of Bacteroides spp. in pure culture form but not that of Lactobacillus or Bifidobacterium spp. However, a low level of bifidogenic activity was observed upon use of mixed culture of B. fragilis and B. longum. The research implies industrial applications of W. cibaria Fiplydextran for the production of high molecular weight dextran with better yield.

Optimization and Production of Exopolysaccharides (EPS) and Indole-3-Acetic Acid (IAA) Under Chromium by Halophilic Bacteria Oceanobacillus oncorhynchi W4.

The current study assessed the levels of exopolysaccharides (EPS) and indole-3-acetic acid (IAA) and the impacts of halophilic bacteria Oceanobacillus oncorhynchi W4 under Cr (VI). The effects of W4 were tested for its ability to remove Cr (VI) at several concentrations, the removal rate was reached after 48h at 58.4%, 53.3%, 49.2%, and 43.1%). After 12-48h, the maximum removal rate of 29-58% was found at an initial concentration of 50mg/L (Cr (VI)). The Box-Behnken design based on response surface methodology was utilized to optimize the EPS, including pH, sucrose concentration, and incubation period. The highest EPS yield (314.5mg/L) was obtained under 96h at pH 7.0, with 5% sucrose concentration. The strain Oceanobacillus oncorhynchi W4 was tested for its ability to create EPS at various concentrations of Cr (VI). After 96h, it generated the maximum amount of EPS (216.3mg/L) at a concentration of 50mg/L. By using FT-IR spectrum measurements, it was confirmed that hexavalent chromium and EPS had surface chemical interactions. At various Cr (VI) concentrations, the isolate W4 was tested for its ability to secrete Indole-3 acetic acid. IAA secretion (control) without Cr (VI) achieved a maximum of 1.45mg/ml at 120h. At 200mg/L Cr (VI) concentration, 1.65mg/ml of IAA was also produced after 48h. According to the findings, Oceanobacillus oncorhynchi W4 was a promising isolate in a stressful environment.

Bioprospecting for new exopolysaccharide-producing microalgae of marine origin.

Microalgae are photosynthetic organisms that can produce biomolecules with industrial interest, including exopolysaccharides (EPS). Due to their structural and compositional diversity, microalgae EPS present interesting properties that can be considered in cosmetic and/or therapeutic areas. Seven microalgae strains from three different lineages, namely Dinophyceae (phylum Miozoa), Haptophyta, and Chlorophyta, were investigated as EPS producers. All strains were found to be EPS producers, though the highest EPS yield was obtained for Tisochrysis lutea, followed by Heterocapsa sp. (126.8 and 75.8 mg L-1, respectively). Upon assessment of the polymers' chemical composition, significant contents of unusual sugars, including fucose, rhamnose, and ribose, were found. Heterocapsa sp. EPS stood out due to its high content of fucose (40.9 mol%), a sugar known to confer biological properties to polysaccharides. The presence of sulfate groups (10.6-33.5 wt%) was also noticed in the EPS produced by all microalgae strains, thus contributing to the possibility that these EPS might have biological activities worth exploring.

L. A. Ulakhanova, S. V. Gomboeva, V. Zh. Tsyrenov

Silicate bacteria have a wide biotechnological potential, they produce a large number of biologically active substances: enzymes that destroy silicates; fungicidal and antimicrobial compounds; phytohormones and exopolysaccharides (EPS). At the same time, they are able to use silicon-containing minerals as a source of additional energy. The literature provides studies on the destruction of polysilicon compounds by silicate bacteria of the speciessilicate bacteria. They are capable of destroying quartz, aluminosilicates with the release of Si, K and other elements. There is also information about stimulating the reproduction of silicate bacteria when growing on mineral media with the addition of silicon-containing components. At the same time, the influence of polysilicon compounds on the synthesis of exopolysaccharides by silicate bacteria is not considered. The exoglycans released by them are used in various industries: mining, oil production, pharmaceutical, food and cosmetic. The studies used isolated pure cultures of silicate bacteria, the biosynthetic activity of which was compared with strains of Paenibacillus mucilaginosus B7519 and B4901 (VKPM, GosNIIgenetics). Bacteria were isolated from the soils and sand of the Baikal region. The influence of silicon-containing components (bentonite, quartz sand) of the nutrient medium on crop growth and EPS synthesis was investigated. The positive effect of silicate minerals on the growth of isolated strains and museum cultures of P. mucilaginosus has been confirmed. Strain B-4901 had the highest amount of CFU/ml on nutrient media with both quartz sand and bentonite. The influence of siliconcontaining components on the EPS yield of the studied microorganisms has been established. The highest EPS yield was observed in the VSGUTU-2 strain on a nutrient medium with the addition of quartz sand, and the B7519 strain had the best synthesis on a medium with the addition of bentonite. The VSGUTU-1 strain showed the same yield of exopolysaccharides on two variants of media with silicon-containing components, whereas the amount of EPS in the B4901 strain did not increase with the addition of bentonite and quartz sand. The lowest EPS yields were on nutrient media without the addition of a silicon source.

Safety and robustness aspects analysis of Lactobacillus delbrueckii ssp. bulgaricus LDB-C1 based on the genome analysis and biological tests.

Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus) is a microaerophylic anaerobe, which is widely used in the production of yogurt, cheese, and other fermented dairy products. L. bulgaricus and its partner Streptococcus thermophilus were used as starter cultures of yogurt in the world for thousands of years. In our previous study, L. bulgaricus LDB-C1 was obtained from traditional fermented milk, and possessed some characteristics like high exopolysaccharide yield and good fermentation performance. The analysis of its CRISPR-Cas system, antibiotic resistance, virulence factors, and mobile elements, was performed to reveal the stability of the strain LDB-C1. It was found that LDB-C1 contains a plenty of spacers in the CRISPR region, indicating it might have better performance against the infection of phages and plasmids. Furthermore, the acquired or transmittable antibiotic resistance/virulence factor genes were absent in the tested L. bulgaricus strain LDB-C1.

Response of Lactobacillus plantarum VAL6 to challenges of pH and sodium chloride stresses

To investigate the effect of environmental stresses on the exopolysaccharide biosynthesis, after 24 h of culture at 37 °C with pH 6.8 and without sodium chloride, Lactobacillus plantarum VAL6 was exposed to different stress conditions, including pH (pHs of 3 and 8) and high sodium chloride concentration treatments. The results found that Lactobacillus plantarum VAL6 exposed to stress at pH 3 for 3 h gives the highest exopolysaccharide yield (50.44 g/L) which is 6.4 fold higher than non-stress. Under pH and sodium chloride stresses, the mannose content in exopolysaccharides decreased while the glucose increased in comparison with non-stress condition. The galactose content was highest under stress condition of pH 8 meantime rhamnose content increased sharply when Lactobacillus plantarum VAL6 was stressed at pH 3. The arabinose content in exopolysaccharides was not detected under non-stress condition but it was recorded in great amounts after 3 h of stress at pH 3. In addition, stress of pH 8 triggered the mRNA expression of epsF gene resulting in galactose-rich EPS synthesis. According to our results, the stresses of pH and sodium chloride enhance the production and change the mRNA expression of epsF gene, leading to differences in the monosaccharide composition of exopolysaccharides.

The isolation of exopolysaccharide-producing lactic acid bacteria from lontar (Borassus flabellifer L.) sap.

Background and Objectives:Lontar (Borassus flabellifer L.) is widely grown in Indonesia and one of its products is palm sap. Palm sap contains a high level of sugar, making it suitable as a medium to increase the lactic acid bacteria (LAB) production of exopolysaccharides (EPS). This study aimed to isolate the EPS-producing LAB from palm sap and evaluate its EPS production. LAB isolation was carried out on MRS agar containing 0.5% CaCO3.Materials and Methods:The screening and production of EPS were carried out on MRS media supplemented with 10% sucrose. The molecular identification of the selected EPS-producing LAB was based on 16S rDNA. A quantitative analysis of EPS polymer dry mass and total sugar was conducted using one-way ANOVA.Results:In this study, five EPS-producing LABs were found: Fructobacillus fructosus N4, Leuconostoc mesenteroides N5, Leuconostoc mesenteroides N7, Leuconostoc mesenteroides N9, and Fructobacillus fructosus N10. The highest EPS yield in liquid media was 10.997 ± 1.591 g/L by Leuconostoc mesenteroides N7, whereas the lowest was 4.505 ± 0.459 g/L by Fructobacillus fructosus N10.Conclusion:This study found Fructobacillus fructosus strains as EPS producers that have never been reported before.

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.

Evaluation of the production of exopolysaccharides by newly isolated Halomonas strains from Tunisian hypersaline environments

Ten Halomonas strains were screened from different Tunisian hypersaline environments for the production of exopolysaccharides (EPS), characterized and identified basing on 16S rRNA gene sequencing. EPS production was therefore studied using two different culture media M1 (complex medium) and M2 (semi-complex medium). Selected isolates produced different EPS amounts ranging from 86 to 170 mg L−1 and 26 to 105 mg L−1 when grown on M1 and M2, respectively. The use of M1 encouraged stronger bacterial growth associated with greater EPS production compared to M2. Nevertheless, the highest EPS yield (YEPS/X) was observed for strains grown on M2. When cultivated on M1, all isolates produced EPS exhibiting almost the same monosaccharide profile with mannose, glucose and arabinose being the main monomers. However, the produced EPS on M2 were characterized by heterogeneous monosaccharide profiles among the different species, mostly consisting of glucomannan that could be a versatile material used for many further applications.

Immunomodulatory effects of exopolysaccharides produced by Bacillus licheniformis and Leuconostoc mesenteroides isolated from Korean kimchi

The immunomodulatory properties of exopolysaccharides (EPS), major components of bacterial biofilm, are not fully understood. Here, we examined the immunomodulatory potential of EPS derived from Bacillus licheniformis BioE-BL11 and Leuconostoc mesenteroides BioE-LMD18, isolated from Korean fermented kimchi. EPS from BioE-BL11 was composed of mannose (12.4%), galactose (1.82%), glucose (48.5%), fucose (37.1%), and arabinose (0.17%), and that from BioE-LMD18 was composed of mannose (8.71%), arabinose (0.07%), galactose (1.22%), glucose (79.8%), and fucose (10.21%). The highest EPS yield were obtained by incubation at 37 °C for 3 days with an initial pH of 7.0, without optimizing other conditions. The EPS from BioE-BL11 and BioE-LMD18 significantly inhibited secretion of the pro-inflammatory cytokine IL-6 in lipopolysaccharide-stimulated RAW264.7 mouse macrophage by 40.7% and 32.1%, respectively, enhanced secretion of the anti-inflammatory cytokine IL-10 in a dose-dependent manner, suggesting that EPS produced by these strains may be useful functional ingredients for the cosmetics, food, and pharmaceuticals industries.

Metabolic profiling of Antarctic yeasts by proton nuclear magnetic resonance-based spectroscopy

The continent of Antarctica, as a combination of constantly low temperatures, strong winds, short summer season, and high solar radiation, is a highly extreme habitat suggesting appropriate conditions for growth of psychrophilic microorganisms. Five psychrophilic yeast strains were isolated from the samples taken from the region of the Bulgarian Base on Livingston Island, Antarctica: Cryptococcus laurentii AL65, Sporobolomyces salmonicolor AL36, Debaryomyces hansenii, Leucosporidium scotii and Rhodotorula glutinis, and their biomass yield and exopolysaccharides production were investigated. Best growth was observed for L. scotii and C. laurentii AL65, with 7.5 and 6.0 g/L biomass, respectively, and highest exopolysaccharide yield was established for L. scotii. Metabolic profiling revealed phylogenetically based diversity in the identified metabolic profiles. The proton nuclear magnetic resonance (1H NMR) spectroscopy analyses of compounds extracted from the biomass of the strains revealed significant differences in the metabolites between individual yeast strains in our investigation including: among the amino acids alanine, valine, threonine, leucine and tyrosine; some organic acids such as gamma-aminobutyric acid, acetic acid, formic acid and others. Glucose was identified in all investigated strains. The highest diversity of compounds was observed in D. hansenii strain, division Ascomycota. The main compounds in the metabolic profile of Basidiomycota strains were sugars. The statistical analysis revealed significant differences in the studied metabolites among the yeast strains. This result suggests that, together with 16S rRNA gene and enzyme gene analyses, metabolite profiling could be also used as a marker for a phylogenetic distance in fungi evolution.

Characterization and antibacterial activity of a novel exopolysaccharide produced by Lactobacillus kefiranofaciens DN1 isolated from kefir

Kefir is fermented milk produced by co-cultures of lactic and acetic acid bacteria and yeast that are encapsulated by an exopolysaccharide (EPS) called kefiran. Probiotic kefir provides many benefits, including antimicrobial effects against many pathogens. The mechanisms underlying these effects, however, are not yet completely understood. In this study, a total of 22 strains of lactic acid bacteria (LAB), including eight strains of Lactobacillus kefiranofaciens, two strains of Lactobacillus kefiri, seven strains of Lactococcus lactis, and five strains of Leuconostoc mesenteroides, were isolated from kefir and classified by 16S ribosomal RNA gene sequencing. The ability of each strain to produce EPS was determined, and Lactobacillus kefiranofaciens DN1 was found to have the highest EPS yield among all isolates. Lactobacillus kefiranofaciens DN1 produced EPS, using glucose and lactose, and EPS yield rose to 2.2 g/L in modified MRS broth (60 g/L glucose). The antimicrobial activities of the EPS produced by Lactobacillus kefiranofaciens DN1 (EPS_DN1) against Listeria monocytogenes and Salmonella Enteritidis were assessed by growth curve analysis. We found that EPS_DN1 at a concentration of at least 1% was able to exert bactericidal effects against both pathogens. Notably, results of high-performance size-exclusion chromatography (HPSEC) analysis indicated that EPS_DN1 was not kefiran, the major EPS of kefir grains, suggesting that EPS_DN1 represents a novel bioactive compound in kefir.

The exopolysaccharides biosynthesis by Candida yeast depends on carbon sources

Background: The exopolysaccharides (EPS) produced by yeast exhibit physico-chemical and rheological properties, which are useful in the production of food and in the cosmetic and pharmaceutical industries as well. The effect was investigated of selected carbon sources on the biosynthesis of EPS by Candida famata and Candida guilliermondii strains originally isolated from kefirs. Results: The biomass yields were dependent on carbon source (sucrose, maltose, lactose, glycerol, sorbitol) and ranged from 4.13 to 7.15 g/L. The highest biomass yield was reported for C. guilliermondii after cultivation on maltose. The maximum specific productivity of EPS during cultivation on maltose was 0.505 and 0.321 for C. guilliermondii and C. famata , respectively. The highest EPS yield was found for C. guilliermondii strain. The EPS produced under these conditions contained 65.4% and 61.5% carbohydrates, respectively. The specific growth rate ( μ ) of C. famata in medium containing EPS as a sole carbon source was 0.0068 h -1 and 0.0138 h -1 for C. guilliermondii strain. Conclusions: The most preferred carbon source in the synthesis of EPS for both Candida strains was maltose, wherein C. guilliermondii strain showed the higher yield of EPS biosynthesis. The carbon source affected the chemical composition of the resulting EPS and the contribution of carbohydrate in the precipitated preparation of polymers was higher during supplementation of maltose as compared to sucrose. It was also found that the EPS can be a source of carbon for the producing strains.

Comparison of Thraustochytrids Aurantiochytrium sp., Schizochytrium sp., Thraustochytrium sp., and Ulkenia sp. for Production of Biodiesel, Long-Chain Omega-3 Oils, and Exopolysaccharide

Heterotrophic growth of thraustochytrids has potential in coproducing biodiesel for transportation, as well as producing a feedstock for omega-3 long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA), especially docosahexaenoic acid (DHA) for use in nutraceuticals. In this study, we compared eight new endemic Australian thraustochytrid strains from the genera Aurantiochytrium, Schizochytrium, Thraustochytrium, and Ulkenia for the synthesis of exopolysaccharide (EPS), in addition to biodiesel and LC-PUFA. Aurantiochytrium sp. strains readily utilized glucose for biomass production, and increasing glucose from 2 to 4 % w/v of the culture medium resulted in increased biomass yield by an average factor of 1.7. Ulkenia sp. strain TC 010 and Thraustochytrium sp. strain TC 033 did not utilize glucose, while Schizochytrium sp. strain TC 002 utilized less than half the glucose available by day 14, and Thraustochytrium sp. strain TC 004 utilized glucose at 4 % w/v but not 2 % w/v of the culture suggesting a threshold requirement between these values. Across all strains, increasing glucose from 2 to 4 % w/v of the culture medium resulted in increased total fatty acid methyl ester content by an average factor of 1.9. Despite an increasing literature demonstrating the capacity of thraustochytrids for DHA synthesis, the production of EPS from these organisms is not well documented. A broad range of EPS yields was observed. The maximum yield of EPS was observed for Schizochytrium sp. strain TC 002 (299 mg/L). High biomass-producing strains that also have high lipid and high EPS yield may be better candidates for commercial production of biofuels and other coproducts.

Influence of casein hydrolysates on exopolysaccharide synthesis byStreptococcus thermophilusandLactobacillus delbrueckiissp.bulgaricus

A lot of interesting research has been undertaken to enhance the yield of exopolysaccharides (EPS) produced by lactic acid bacteria (LAB). The objective of this study was to determine the influence of casein hydrolysates (CH) with molecular weight less than 3 kDa on cell viability, EPS synthesis and the enzyme activity involved in EPS synthesis during the co-culturing of Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus in MRS broth for 72 h at 37 ± 0.1 °C. The highest EPS yield (150.1 mg L⁻¹) was obtained on CH prepared with papain (CHP) at 48 h. At 24 h, EPS were composed of galactose, glucose and rhamnose in a molar ratio of 1.0:2.4:1.5. The monosaccharide composition changed with extension of the fermentation time. The activities of α-phosphoglucomutase, uridine 5'-diphosphate (UDP)-glucose pyrophosphorylase and UDP-galactose 4-epimerase were associated with EPS synthesis. Moreover, the activities of β-phosphoglucomutase and deoxythymadine 5'-diphosphate (dTDP)-glucose pyrophosphorylase involved in rhamnose synthesis were very low at the exponential growth phase and could not be detected during other given periods. The influence of different CH (<3 kDa) on LAB viability, EPS production, EPS monomeric composition and activity levels of key metabolic enzymes was distinct. Besides, their influence was related to the distribution of amino acids.

New bacilli from shallow hydrothermal vents of Panarea Island (Italy) and their biotechnological potential

To characterize bacilli isolated from shallow hydrothermal vents of Panarea Island (Italy) and evaluate their biotechnological potential. Fifteen isolates were characterized by culture and molecular methods. Eleven isolates were thermophilic, six isolates were alkalophilic and four of them were haloalkalophilic. After 16S rRNA gene sequencing, four strains, exhibiting sequence similarity below 95% with deposited strains, may represent novel species of bacilli. One strain was strictly related to Geobacillus subterraneus, but shared phenotypic characteristics for which it could be considered a new strain of this species. Four strains were affiliated with different Bacillus spp. Most isolates produced gelatinase, lipases and amylase, and some were mercury tolerant. Exopolysaccharides (EPS) production was tested adding different sugars (glucose, sucrose, trehalose, fructose, ribose, xylose and mannose, 1% w/v) as a carbon source in a minimal medium. The highest EPS yield (185 mg l(-1)) was reached by strain 1A70 utilizing ribose as a carbon source. Novel strains of Geobacillus and indigenous ribotypes of Bacillus with biotechnological potential inhabit shallow vents of Panarea Island. New strains of thermophilic bacilli from Panarea are producers of useful biomolecules for industrial purposes as well as environmental and biotechnological applications.

Enhanced exopolysaccharide production by metabolic engineering of Streptococcus thermophilus.

It is possible that the low levels of production of exopolysaccharides (EPSs) by lactic acid bacteria could be improved by altering the levels of enzymes in the central metabolism that influence the production of precursor nucleotide sugars. To test this hypothesis, we identified and cloned the galU gene, which codes for UDP glucose pyrophosphorylase (GalU) in Streptococcus thermophilus LY03. Homologous overexpression of the gene led to a 10-fold increase in GalU activity but did not have any effect on the EPS yield when lactose was the carbon source. However, when galU was overexpressed in combination with pgmA, which encodes phosphoglucomutase (PGM), the EPS yield increased from 0.17 to 0.31 g/mol of carbon from lactose. A galactose-fermenting LY03 mutant (Gal(+)) with increased activities of the Leloir enzymes was also found to have a higher EPS yield (0.24 g/mol of carbon) than the parent strain. The EPS yield was further improved to 0.27 g/mol of carbon by overexpressing galU in this strain. However, the highest EPS yield, 0.36 g/mol of carbon, was obtained when pgmA was knocked out in the Gal(+) strain. Measurements of the levels of intracellular metabolites in the cultures revealed that the Gal(+) strains had considerably higher glucose 1-phosphate levels than the other strains, and the strain lacking PGM activity had threefold-higher levels of glucose 1-phosphate than the other Gal(+) strains. These results show that it is possible to increase EPS production by altering the levels of enzymes in the central carbohydrate metabolism.

Production and characterization of an exopolysaccharide from Rhizobium hedysari HCNT 1

Rhizobium hedysari strain HTCN 1 produces viscous fermentation broths due to the presence of exopolysaccharide (EPS) products. Production of these products has been studied by testing a wide range of C- and N-sources. The highest EPS yield (9.04 g/L) has been obtained after 7 days cultivation in shaken flask on mannitol and lysine. The isolated and purified EPS has been subjected to chemical identification by means of NMR and FTIR spectroscopies.