High Molecular Weight Polysaccharide Research Articles

Simulated human digestion and fermentation of a high-molecular weight polysaccharide from Lentinula edodes mushroom and protective effects on intestinal barrier

Lentinula edodes (Shiitake) is an important edible mushroom and polysaccharides are its major constituents with proven health benefits. The study was to investigate the gut bacterial fermentation and subsequent effects on gut barrier function of a glucan-rich polysaccharide, LePS40 precipitated from the mushroom water extract with 40 % (v/v) ethanol. LePS40 consisted of a β-(1→3)-glucan main chain with substitution in the C-6 position with side chains mainly composed of (1 → 6)-linked β-Glcp residues, (1 → 6)-linked α-Galp residues and terminal residues of β-Glcp. LePS40 was found highly resistant to digestive enzymes and gastric acid in simulated human gastrointestinal tract, but highly fermentable during in vitro human fecal fermentation. The fecal fermentation degradation of LePS40 appeared to selectively break the glucoside linkage in view of the dramatic decrease in the glucose molar ratio (12.68 to 1.07). Compared with the prebiotic reference FOS, LePS40 led to much higher levels of butyric, and propionic acid and a lower level of acetic acid. Moreover, LePS40 enhanced the abundance of some beneficial bacterial populations, but decreased the bacteria possibly linked with fatty-liver disease and colorectal cancer. Furthermore, the fecal fermentation products of LePS40 showed a potential protective effect on intestinal barrier function against inflammatory damage in Caco-2/Raw264.7 co-culture model. These findings suggest the potential of LePS40 for improvement of gut health through modulation of gut microbiota.

UV-C Treatment Impact on the Availability of Water-Soluble Carbohydrates, Polyphenols, and Antioxidant Capacity of an Algerian Underutilized Date Fruit (Phoenix dactylifera L.).

Underutilized dates are considered as a socioeconomically important fruit for local and global communities, such as Degla-Beida, a common date fruit variety. The aim of this research was to elucidate, for the first time, the efficiency of UV-C light treatment (over different irradiation durations 5, 10, 20, and 40 min) in the enhancement of soluble carbohydrates and phenolic compounds, and to evaluate its effect on the antioxidant capacity. Furthermore, the content of dietary fiber was analyzed: insoluble dietary fiber (11.89 g/100 g); soluble dietary fiber (5.15 g/100 g); and total dietary fiber (17.06 g/100 g). The techno-functional properties were also determined: swelling capacity (3.94 mL/g); oil holding capacity (7.38 g/g); water holding capacity (9.30 g/g); and bulk density (1.81 g/mL). All were carried out to study the potential of exploiting this underutilized fruit for other applications as for feed or food. The results suggest that UV-C technology changes minimally the total water-soluble carbohydrate content; however, this preservation technology can affect the availability of different soluble carbohydrates depending on the irradiation time (IT), increasing the high molecular weight polysaccharides with IT up to 20 min, and some oligosaccharides with IT up to 5 min. The polyphenolic content determined by HPLC-QTOF was increased when the samples were submitted to UV-C reaching the maximum at 20 min (111.62 mg/100 g) and then to decrease in those submitted to IT of 40 min (12.05 mg/100 g). Regarding antioxidant capacity in the UV-C treated samples, FRAP decreased and EC50 on DPPH increased when IT was increased, while ORAC was hardly maintained. In addition, considering UV-C radiation associated with preservation and the studied date fruit as a rich source of dietary fiber with adequate techno-functional properties, this study presents valuable information for its potential use as a new food ingredient.

Safety and efficacy of a class II medical device based on highly purified and standardized plant extracts in the management of post-menopausal patients with vulvar and vaginal atrophy: a single-center prospective observational study.

Despite the gold standard treatment for genitourinary syndrome of menopause (GSM) is based on the use of local or systemic estrogen-containing products, the typical long-term side effects of hormonal treatments and, most importantly, the contraindications in patients with history of breast and endometrial neoplasms do limit in some extent its use. As hyaluronic acid and some highly purified botanicals have clearly demonstrated their anti-inflammatory and mucosa-protecting properties, we have tested, in women with GSM, a class II vaginal medical device containing hyaluronate gel and a mucoadhesive active enriched with purified alkylamides from Zanthoxylum bungeanum, triterpenes from Centella asiatica and high molecular weight polysaccharides from Tamarindus indica. Our single-center, open-label, prospective and observational study was conducted on 50 menopausal women enrolled at the Department of Maternal-Fetal Medicine at Umberto I Polyclinic Hospital in Rome, Italy. Gel administration lasted 150 days and was performed daily for the first 12 days and every 48 hours for the remaining 138 days. Clinical evaluations were performed at baseline and after 12, 57 and 150 days. Besides product safety, main outcomes of our study were: 1) vaginal health (by Vaginal Health Index score [VHI]); 2) sexual quality of life (by Female Sexual Distress Scale [FSDS]); and 3) percentage of women declaring regular sexual activity. The product was safe with no specific adverse events reported. It significantly improved VHI (about 5% after 57 days and 8% after 150 days), FSDS (about 7% after 57 days and 10% after 150 days), and sexual activity (about 20% after 150 days). It also reduced dryness, dyspareunia, burning, itching, and dysuria incidence, respectively by about 18%, 14%, 14%, 27% and 11% after 150 days. In women with GSM, the intravaginal administration of a hyaluronate-based gel enriched with purified botanical actives endowed with anti-inflammatory and mucosal-protecting properties, reduced painful sensation during sexual acts and increased regular sexual activity.

Characterization of the Antiproliferative Activity of Sargassum muticum Low and High Molecular Weight Polysaccharide Fractions.

The extract obtained by pressurized hot water extraction from Sargassum muticum, to recover the bioactive compound known as fucoidan, was fractionated using membranes of 100, 50, 30, 10, and 5 kDa, obtaining five retentates and the final permeate. These fractions were characterized for phloroglucinol content, protein content, sulfate content, and trolox equivalent antioxidant capacity (TEAC); apart from oligosaccharides, FTIR and molar mass distribution were also evaluated. Retentates of 100 and 50 kDa showed higher values for phloroglucinol, TEAC, and sulfate content. The rheology of the alginate fraction was also evaluated. Regarding the potential antitumoral activity, all fractions were assessed in MCF-7 cells using a metabolic activity assay based on the reduction of a tetrazolium compound, the most efficient being R100 and R50. Based on the results, these fractions were compared with commercial fucoidans at the same concentrations, and similar results were found. In addition, synergistic cytotoxic effects using two drugs commonly used in breast cancer, cis-Platinum (cis-Pt) and 5-fluorouracil (5-FU), were tested in combination with R100 and R50. Promising results were obtained when the retentate and the drugs were mixed, showing an improvement in the cytotoxicity induced by the chemotherapy.

Kyselina hyaluronová – význam a možnosti využití v otorinolaryngologii

kyselina hyaluronová – otorinolaryngologie – léčba Summary Hyaluronic acid (HA) is a linear, naturally occurring polysaccharide of high molecular weight. It is part of a number of bio logical processes, especially regulatory, anti-inflammatory, immunosuppressive or antiproliferative. It significantly binds water and participates in the maintenance of tissue viscoelasticity, in the supramolecular spatial arrangement of proteoglycans in the extracellular matrix and in the regulation of osmotic pressure, which significantly affects tissue homogeneity and its homeostatic integrity. Due to these properties, non-immunogenic HA can be used in many clinical applications. In otorhinolaryngology, the possibilities of its use are wide, especially in otology, laryngology, rhinology or in the treatment of inflammatory conditions and keloid scars. Some potential areas of use are still in the experimental stage (gene therapy). Key words hyaluronic acid – otorhinolaryngology – treatment

Oral sodium hyaluronate relieves knee discomfort: A 12‑week double‑blinded, placebo‑controlled study.

Sodium hyaluronate (SH) is a high molecular-weight polysaccharide composed of repeating polymeric disaccharides of D-glucuronic acid and N-acetyl-D-glucosamine. SH is present in every connective tissue and organ, with synovial fluid having the highest concentration of SH in the body. The effectiveness of oral SH on gonarthrosis is known; although, its influence on the knees of healthy individuals is not. However, as severe diseases may require surgery, it is better to take care of healthy knees before the onset of gonarthrosis. Therefore, the present study investigated the functionality of SH on the knee of healthy individuals. The present study was a randomized double-blind, placebo-controlled trial in which healthy adults (mean age: Placebo group, 61.50±1.59; SH group, 58.50±1.81), rated as grade ≤1 based on the Kellgren-Lawrence classification, were administered 111 mg/day SH for 12 weeks. The evaluation of visual analog scales were performed to assess the discomfort in the knees of the participants and were conducted at baseline, and then 6 and 12 weeks after the start of SH ingestion. Additionally, a locomotive syndrome risk test quantifying the mobility of the participants, a one-leg standing time with eyes open test evaluating the strength of the leg muscle as well as the ability to balance by measuring the time to stand on one leg and a blood test (interleukin-10, aspartate aminotransferase, alanine transaminase, γ-glutamyl transferase, lactate dehydrogenase, creatine kinase and C-reactive protein) were performed at baseline and then 12 weeks after the start of SH ingestion. A significant suppression of knee symptoms were demonstrated in the SH group compared with the placebo group in terms of the total visual analog scale scores for pain, stiffness and discomfort for the 31 healthy adult subjects. Significant suppression of symptoms was also demonstrated in the placebo group in terms of discomfort in the knees when descending stairs and pain in the knees after walking for a longer distance or duration than normal. No significant differences between the two groups were demonstrated in the locomotive syndrome risk test, one-leg standing time with eyes open test and the blood test. The results of the present study suggest the possibility that oral SH may help to maintain a healthy condition of the knees. The study protocol was registered with the University Hospital Medical Information Network Clinical Trial Registry in advance (registration no. UMIN000045980, November 4, 2021).

Harnessing root exudates for plant microbiome engineering and stress resistance in plants

A wide range of abiotic and biotic stresses adversely affect plant's growth and production. Under stress, one of the main responses of plants is the modulation of exudates excreted in the rhizosphere, which consequently leads to alterations in the resident microbiota. Thus, the exudates discharged into the rhizospheric environment play a preponderant role in the association and formation of plant-microbe interactions. In this review, we aimed to provide a synthesis of the latest and most pertinent literature on the diverse biochemical and structural compositions of plant root exudates. Also, this work investigates into their multifaceted role in microbial nutrition and intricate signaling processes within the rhizosphere, which includes quorum-sensing molecules. Specifically, it explores the contributions of low molecular weight compounds, such as carbohydrates, phenolics, organic acids, amino acids, and secondary metabolites, as well as the significance of high molecular weight compounds, including proteins and polysaccharides. It also discusses the state-of-the-art omics strategies that unveil the vital role of root exudates in plant-microbiome interactions, including defense against pathogens like nematodes and fungi. We propose multiple challenges and perspectives, including exploiting plant root exudates for host-mediated microbiome engineering. In this discourse, root exudates and their derived interactions with the rhizospheric microbiota should receive greater attention due to their positive influence on plant health and stress mitigation.

Polysaccharide of Asparagus cochinchinensis (Lour.) Merr: Preliminary characterization and antitumor activity in vivo

A novel high molecular weight polysaccharide (ACP) extracted and purified from Asparagus cochinchinensis (Lour.) Merr was preliminarily characterized by HPGPC, Ion chromatography, FT-IR, NMR, and SEM, and its in vivo antitumor activity was investigated using an H22 tumor-bearing mice model. ACP was identified to be a homogeneous component with a purity of 95.75 ± 1.58%, a molecular weight of 74.7 kDa, and an acidic polysaccharide composed of Rha, Ara, Gal, Glc, Xyl, Man, GalA, and GlcA at a molar ratio of 0.34:1.86:8.72:15.99:1:0.52:2.25:0.11 with α- and β-anomeric units. In vivo antitumor activity evaluation showed that ACP could effectively inhibit the growth of solid tumors in H22 hepatocellular carcinoma-transplanted mice at inhibition rates of 26.5% and 45.3%, respectively, with the two possible apoptosis mechanisms involving arresting the cell cycle in G0/G1 phase and reducing the mitochondrial membrane potential in H22 cells. These results indicate the potential of ACP as a therapeutic agent of liver cancer.

Marine versus Non-Marine Bacterial Exopolysaccharides and Their Skincare Applications.

Bacteria are well-known to synthesize high molecular weight polysaccharides excreted in extracellular domain, which constitute their protective microenvironment. Several bacterial exopolysaccharides (EPS) are commercially available for skincare applications in cosmetic products due to their unique structural features, conferring valuable biological and/or textural properties. This review aims to give an overview of bacterial EPS, an important group of macromolecules used in cosmetics as actives and functional ingredients. For this purpose, the main chemical characteristics of EPS are firstly described, followed by the basics of the development of cosmetic ingredients. Then, a focus on EPS production, including upstream and downstream processes, is provided. The diversity of EPS used in the cosmetic industry, and more specifically of marine-derived EPS is highlighted. Marine bacteria isolated from extreme environments are known to produce EPS. However, their production processes are highly challenging due to high or low temperatures; yield must be improved to reach economically viable ingredients. The biological properties of marine-derived EPS are then reviewed, resulting in the highlight of the challenges in this field.

Microbial modifications with Lycium barbarum L. oligosaccharides decrease hepatic fibrosis and mitochondrial abnormalities in mice.

Lycium barbarum L. is a typical Chinese herbal and edible plant and are now consumed globally. Low molecular weight L. barbarum L. oligosaccharides (LBO) exhibit better antioxidant activity and gastrointestinal digestibility in vitro than high molecular weight polysaccharides. However, the LBO on the treatment of liver disease is not studied. Modification of the gut microbial ecosystem by LBO is a promising treatment for liver fibrosis. Herein, LBO were prepared and characterized. CCl4-treated mice were orally gavaged with LBO and the effects on hepatic fibrosis and mitochondrial abnormalities were evaluated according to relevant indicators (gut microbiota, faecal metabolites, and physiological and biochemical indices). The results revealed that LBO, a potential prebiotic source, is a pyranose cyclic oligosaccharide possessing α-glycosidic and β-glycosidic bonds. Moreover, LBO supplementation restored the configuration of the bacterial community, enhanced the proliferation of beneficial species in the gastrointestinal tract (e.g., Bacillus, Tyzzerella, Fournierella and Coriobacteriaceae UCG-002), improved microbial metabolic alterations (i.e., carbohydrate metabolism, vitamin metabolism and entero-hepatic circulation), and increased antioxidants, including doxepin, in mice. Finally, LBO administration reduced serum inflammatory cytokine and hepatic hydroxyproline levels, improved intestinal and hepatic mitochondrial functions, and ameliorated mouse liver fibrosis. These findings indicate that LBO can be utilized as a prebiotic and has a remarkable ability to mitigate liver fibrosis.

Rheological investigation of the network structure in mixed gels of Kappa and Iota Carrageenan

Carrageenans comprise linear sulfated high molecular weight polysaccharides obtained from seaweeds and are routinely used in food and home/personal care industries. Various kinds of carrageenans differ from others based on the ester sulphate group location on the polysaccharide chains. Pure and mixed systems of Kappa Carrageenan and Iota Carrageenan undergo a three-dimensional gel network structure formation or dissociation with a change in temperature. During the sol-gel and gel-sol transitions, the Carrageenan systems pass through a unique critical gel state, where dynamic moduli are scale-invariant owing to the self-similar structure of the three-dimensional network. In this work, we obtain the critical gel state associated with pure and mixed systems of Kappa and Iota Carrageenan during cooling and heating by exploring the material behavior for a range of frequencies. Interestingly, on the one hand, the mixed gels show a higher critical sol-gel transition temperature compared to the pure systems at equal individual concentrations. On the other hand, the low temperature moduli of mixed gels are closer to that of Kappa Carrageenan when the concentration of the same is more than half in the mixture. The rheological measurements demonstrate that the Kappa Carrageenan strongly affects the nature of aggregation of double helices of Iota Carrageenan, but Iota Carrageenan does not have a significant influence on that of Kappa Carrageenan. These results suggest an associative, interactive network formation between Kappa and Iota Carrageenan in the mixture, such that the gel behavior is predominantly influenced by Kappa Carrageenan.

Production and composition of extracellular polymeric substances by a unicellular strain and natural colonies of Microcystis: Impact of salinity and nutrient stress.

The transfer of toxic cyanobacterial Microcystis blooms from freshwater to estuaries constitutes a serious environmental problem worldwide that is expected to expand in scale and intensity with anthropogenic and climate change. The formation and maintenance of Microcystis in colonial form is conditioned to the presence of extracellular polymeric substances (EPS). In this study, we attempted to better understand how the mucilaginous colonial form of Microcystis evolves under environmental stress conditions. In particular, we studied and compared the production and the composition of EPS fractions (attached and free) from natural colonies of a Microcystis bloom and from a unicellular M. aeruginosa strain under salinity and nutrient stress (representing a land-sea continuum). Our results highlighted a greater production of EPS from the natural colonies of Microcystis than the unicellular one under nutrient and combined stress conditions dominated by the attached form. In comparison to the unicellular Microcystis, EPS produced by the colonial form were characterized by high molecular weight polysaccharides which were enriched in uronic acids and hexosamines, notably for the free fraction in response to increased salinities. This complex extracellular matrix gives the cells the ability to aggregate and allows the colonial cyanobacterial population to cope with osmotic shock.

Opuntia plants nutritive and medicinal value: a review

The scientific name Opuntia identifies a succulent plant native to Mexico. It is now widespread in the United States, South America and the Mediterranean basin, where it has found a suitable terrain for naturalization. It is a species of cactus popularly known as Nopal in Mexico and “Fico d’India” in Italy. Cladodes, the branched leaves of the plant, are paddle shaped and covered in short spines that enable it to absorb even the tiniest drop of water. A specific and well known type of Opuntia, called Opuntia ficus-indica, can be recognized by its typical yellow flowers and is appreciated for its fleshy fruit with a pleasant taste, rich in nutrients but low in calories. It is used as a foodstuff and in particular to produce juices, jellies and other edible products. The O. ficus-indica is also well known as a source of vitamins, especially vitamin C, calcium and phosphorus and in smaller quantities of other minerals and various essential nutrients, including antioxidants. The cladodes are the part of the plant from which the extract is used to aid weight control and as a cosmetic ingredient with an emollient and soothing action. The spongy tissues of the cladodes contain high concentrations of high molecular weight polysaccharides, which are relevant for the specific properties commonly attributed to this common succulent plant. This review presents several medicinal benefits, which can be obtained using cladodes, fruits and flowers of the different Opuntia species.

Kinetics of acid hydrolysis of k-Carrageenan by in situ rheological follow-up

Water based solutions of κ-Carrageenan (1.5% weight concentration), a high molecular weight polysaccharide, were subjected to acid-catalyzed hydrolysis under controlled pH (≈3) and temperature (from 40 to 70 °C). The hydrolysis process involves selective attack of the Carrageenan glycosidic bonds α(1–3) and β(1–4), determining changes in the weight average molecular weight of the macromolecule and, as a consequence, on the gelling behavior. In this study we used transient rheological tests to monitor the hydrolysis reaction and its consequences on both the sol-gel transition and the final gel properties. Hydrolysis reaction has been modelled using a bi-exponential kinetics. To this end, a rotational rheometer was equipped with a batch reactor configuration, consisting of a cylindrical vessel and a double helix mixing tool. Both viscous and viscoelastic properties of the samples were measured quantitatively and related to the biopolymer molecular weight, replacing more complex molecular weight determinations by an easier methodology. By using the above experimental approach, kinetic constants and activation energies for the κ-Carrageenan hydrolysis were obtained as a function of the hydrolysis temperature. The latter, along with the hydrolysis reaction time, was also shown to be a relevant parameter in determining the possibility of gel formation and of the gel mechanical strength (in the range 10–600 Pa).

Changes in the structure of polysaccharides under different extraction methods

Changes in the structure of polysaccharides under different extraction methods

Antimicrobial high molecular weight pectin polysaccharides production from diverse citrus peels using a novel PL10 family pectate lyase

The discovery of environmentally friendly enzymes that can convert inexpensive and abundant citrus peel pectin into high value-added product is a potential avenue for the citrus peel application. In this study, a novel PL10-family pectate lyase (pelA) was characterized from marine bacterium Echinicola pacifica. PelA was a Ca2+ dependent pectate lyase whose activity was highest at pH 8 and 40 °C. It was capable of degrading polygalacturonic acid (PGA) and citrus peel pectin (CPP), but not apple peel pectin. Notably, PelA hydrolyzed PGA to high molecular weight polysaccharide (average molecular weight 111.4 kDa). Moreover, PelA was also able to degrade CPP from nine distinct citrus species into polysaccharides (average molecular weight ranging from 84.7 to 539.2 kDa) that showed antimicrobial activity against Staphylococcus epidermidis (88.8 %), Bacillus subtilis (99.8 %), Staphylococcus aureus (92.1 %), Escherichia coli (100.0 %) and Klebsiella pneumoniae (86.4 %). Considering the high market value of pectin in the food industry, PelA's capacity to convert citrus pectin into high molecular weight polysaccharides lays a foundation for its applications.

Enrichment and application of extracellular nonulosonic acids containing polymers of Accumulibacter.

Pseudaminic and legionaminic acids are a subgroup of nonulosonic acids (NulOs) unique to bacterial species. There is a lack of advances in the study of these NulOs due to their complex synthesis and production. Recently, it was seen that "Candidatus Accumulibacter" can produce Pse or Leg analogues as part of its extracellular polymeric substances (EPS). In order to employ a "Ca. Accumulibacter" enrichment as production platform for bacterial sialic acids, it is necessary to determine which fractions of the EPS of "Ca. Accumulibacter" contain NulOs and how to enrich and/or isolate them. We extracted the EPS from granules enriched with "Ca. Accumulibcater" and used size-exclusion chromatography (SEC) to separate them into different molecular weight (MW) fractions. This separation resulted in two high molecular weight (> 5500kDa) fractions dominated by polysaccharides, with a NulO content up to 4 times higher than the extracted EPS. This suggests that NulOs in "Ca. Accumulibacter" are likely located in high molecular weight polysaccharides. Additionally, it was seen that the extracted EPS and the NulO-rich fractions can bind and neutralize histones. This opens the possibility of EPS and NulO-rich fractions as potential source for sepsis treatment drugs. KEY POINTS: • NulOs in "Ca. Accumulibacter" are likely located in high MW polysaccharides • SEC allows to obtain high MW polysaccharide-rich fractions enriched with NulOs • EPS and the NulOs-rich fractions are a potential source for sepsis treatment drugs.

Cross-linked enzyme aggregates (combi-CLEAs) derived from levansucrase and variant inulosucrase are highly efficient catalysts for the synthesis of levan-type fructooligosaccharides

Efficient and convenient access to short to medium chain length levan-type fructooligosaccharides (LFOS) is needed in order realise the nutritional potential of this class of bioactive oligosaccharides. While LFOS are synthesised by fructansucrase enzymes, these reactions are routinely associated with high molecular weight fructan polymer formation. Recent studies have shown that FOS production can be enhanced by the combination of levansucrase and inulosucrase in a one-pot reaction. In the present study, the novel mixed enzyme cross-linked enzyme aggregates (combi-CLEAs) based on levansucrase (Lev) and N543A variant inulosucrase (Inu) were prepared by ammonium sulfate precipitation, followed by glutaraldehyde cross-linking. The effect of Lev and Inu ratio on the activity of combi-CLEAs was explored. The results showed that >70% of total sucrase activity was recovered after immobilization and that the combi-CLEAs produced high amounts of LFOS (degree of polymerisation 3 to 21), while high molecular weight polysaccharide production was much reduced. Biochemical characterisation indicated that the optimum pH and temperature of combi-CLEAs (pH 5.5 and 50ᵒC, respectively) were comparable to those of free enzyme; however, the stability of the enzyme was improved. In addition, these combi-CLEAs have operational stability for several reaction cycles, which makes them very attractive for biotechnology applications.

Structural characterization of a new high molecular weight polysaccharide from jujube fruit.

From Ziziphus Jujuba cv. Muzao fruit, a new polysaccharide (PZMP3-1) with high molecular weight was isolated. Constructional characterization revealed that PZMP3-1 comprized 2.56 rhamnose, 7.70 arabinoses, 3.73 galactose, and 6.73 galactose, and it has a 241 kDa average molecular weight. The principal structural components of PZMP3-1 were 1,2,4 and 1,4-linked GalpA, 1,4-linked Galp, 1,3 and 1,5-linked Araf, and 1-linked Rhap based on methylation and nuclear magnetic resonance spectroscopy (NMR) analyses. X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), atomic force microscopy (AFM), and scanning electron microscopy (SEM) structural analysis of PZMP3-1 revealed a tangled and branching pattern. Overall, these structural results suggested that PZMP3-1 could have unique bioactivities and be widely used in nutritional supplements.

Diversity of monosaccharides and glycosidic linkages on extracellular polysaccharides of the microalga Ankistrodesmus (Chlorophyceae)

ABSTRACT The diversity of monosaccharides and glycosidic linkages of extracellular polysaccharide (EPS) of high molecular weight were studied in strains morphologically assigned to the genus Ankistrodesmus. EPSs of seven strains were similar in both monosaccharides and glycosidic linkages, but showed exclusive characteristics or enough differences in proportions to distinguish strains. Fucose, glucose, rhamnose, mannose and galactose occurred in relatively high percentages in all strains. The strain CCMA-UFSCar 423, excluded from the genus Ankistrodesmus by the molecular marker tufA, was the only one containing galacturonic acid. Arabinose was found only in one A. densus strain (CCMA-UFSCar 239). The species A. densus and A. stipitatus, which are known to have, respectively, stable mucilaginous capsules and pads in aqueous media, presented high percentages of the hydrophobic fucose and rhamnose on their polysaccharides. However, the strain CCMA-UFSCar 83, the only non-colonial A. densus, had low proportions of rhamnose. We also found variations in glycosidic linkages, and some of them were specific to one strain (e.g. 1-3 glucose in A. stipitatus). Conversely, the absence of common linkages was noteworthy for the strain outside the Ankistrodesmus clade, the CCMA-UFSCar 423. The data revealed important diversity in monosaccharides and linkages of the EPS within a single microalgae genus, and an important intraspecific diversity using a single growing condition. These differences could be useful as potential chemotaxonomic tools to help discriminating the Ankistrodesmus genus or species, but also for future studies on intraspecific diversity within the genus. Moreover, the results show the relevance of studying and conserving closely related strains to preserve biodiversity. The diverse composition of high molecular weight EPSs shows a great potential for prospecting EPSs of economic interest.