Polysaccharide Matrix Research Articles

Cell Wall Matrix Polysaccharides Contribute to Salt–Alkali Tolerance in Rice

Salt-alkali stress threatens the resilience to variable environments and thus the grain yield of rice. However, how rice responds to salt-alkali stress at the molecular level is poorly understood. Here, we report isolation of a novel salt-alkali-tolerant rice (SATR) by screening more than 700 germplasm accessions. Using 93-11, a widely grown cultivar, as a control, we characterized SATR in response to strong salt-alkali stress (SSAS). SATR exhibited SSAS tolerance higher than 93-11, as indicated by a higher survival rate, associated with higher peroxidase activity and total soluble sugar content but lower malonaldehyde accumulation. A transcriptome study showed that cell wall biogenesis-related pathways were most significantly enriched in SATR relative to 93-11 upon SSAS. Furthermore, higher induction of gene expression in the cell wall matrix polysaccharide biosynthesis pathway, coupled with higher accumulations of hemicellulose and pectin as well as measurable physio-biochemical adaptive responses, may explain the strong SSAS tolerance in SATR. We mapped SSAS tolerance to five genomic regions in which 35 genes were candidates potentially governing SSAS tolerance. The 1,4-β-D-xylan synthase gene OsCSLD4 in hemicellulose biosynthesis pathway was investigated in details. The OsCSLD4 function-disrupted mutant displayed reduced SSAS tolerance, biomass and grain yield, whereas the OsCSLD4 overexpression lines exhibited increased SSAS tolerance. Collectively, this study not only reveals the potential role of cell wall matrix polysaccharides in mediating SSAS tolerance, but also highlights applicable value of OsCSLD4 and the large-scale screening system in developing SSAS-tolerant rice.

The water insoluble fraction from red cabbage and black currant pomace reduces the formation of acrylamide, 5-hydroxymethylfurfural and reactive aldehydes in fried potato-based crisps

Plant food by-products are often characterized by a tight matrix of insoluble polysaccharides entrapping bioactive functional molecules. In this study, we investigated the impact of black currant pomace (BC), red cabbage waste (RC) and their water-insoluble fraction (IBC and IRC, respectively) on the formation of Maillard reaction and lipid oxidation products during thermal treatment of potato-based fried crisps. Results showed that the substitution of 20% potato flake with IBC and IRC significantly reduced the formation of acrylamide (14.7%–66.3%) and 5-hydroxymethylfurfural (15.9%–55.4%). This can be explained both by the inhibition of Maillard reaction by plant polyphenols and by the decrease of asparagine and reducing sugars concentration due to the partial replacement of potato flakes. On the opposite, the addition of BC and RC promoted acrylamide and 5-hydroxymethylfurfural formation, which is related to the high amount of reducing carbohydrate in BC and RC. Besides the higher recoveries of extractable polyphenols in IBC- and IRC-enriched crisps, all the four ingredients significantly inhibited the accumulation of 4-hydroxy-2-nonenal, 4-hydroxy-2-hexenal, malondialdehyde and acrolein. These findings highlighted that the elimination of water-soluble compounds is a potential strategy for using plants by-products as efficient ingredients in fried products to limit the formation of processing contaminants.

Effects of Ionizing Radiation on Biopolymers for Applications as Biomaterials

Biopolymers, including extracellular matrix proteins and polysaccharides, are used as substrates for cell culture and scaffolds in tissue engineering. Ionizing radiation, for example with gamma rays or electron beams, is used to sterilize materials and to modify the physical and chemical properties of materials. The principles of the effect of ionizing radiation on biopolymers are discussed in this review article. Among the types of ionizing radiation, gamma rays and electron beams are widely used to sterilize biomaterials and construct medical devices. Water molecules are split by irradiation with ionizing radiation to give hydrated electrons, proton radicals and hydroxyl radicals. These reactive molecular species react with polymer chains to provoke scission or crosslinking reactions. Both the scission and crosslinking of the polymer chains can occur, depending on the types of polymer and irradiation conditions. Sterilization of materials is necessary if they are used in medical devices and implants. The advantages and disadvantages of ionizing radiation in comparison with other methods of sterilization are also discussed. Irradiations with strong gamma rays on the three types of biopolymers—Type I collagen, wool keratin and alginate—are described as examples of biopolymers. Ionizing radiation is a very useful tool for sterilizing materials and constructing medical devices, but it is important that we know its merits and demerits, as well as the limitations, safety and risks, of its applications.

The staphylococcal biofilm protein Aap mediates cell-cell adhesion through mechanically distinct homophilic and lectin interactions.

The accumulation phase of staphylococcal biofilms relies on both the production of an extracellular polysaccharide matrix and the expression of bacterial surface proteins. A prototypical example of such adhesive proteins is the long multidomain protein Aap (accumulation-associated protein) from Staphylococcus epidermidis, which mediates zinc-dependent homophilic interactions between Aap B-repeat regions through molecular forces that have not been investigated yet. Here, we unravel the remarkable mechanical strength of single Aap-Aap homophilic bonds between living bacteria and we demonstrate that intercellular adhesion also involves sugar binding through the lectin domain of the Aap A region. We find that the mechanical force needed to unfold individual β-sheet-rich G5-E domains from the Aap B-repeat regions is very high, ranging from 300 up to 1,000 pN at high loading rates, indicating these are extremely stable. This high mechanostability provides a means to the cells to form highly adhesive and cohesive biofilms capable of sustaining high physiological shear stress. Importantly, we identify a previously undescribed role of Aap in bacterial-bacterial adhesion, that is, heterophilic sugar binding by a specific lectin domain located in the N-terminal A region, which might be important to establish initial contacts between cells before strong homophilic bonds come into play. This study emphasizes the remarkable mechanical and binding properties of Aap as well as its wide diversity of adhesive functions.

Citrus pectin based complexes for the tetracycline delivery

This research studied the formation of sodium polygalacturonate complexes with the antimicrobial drug "Tetracycline". The formation was confirmed by IR, UV and NMR spectroscopy. It was shown that the complexes were formed by electrostatic attraction and hydrogen bonding. The complexes demonstrated a high degree of drug binding to the polysaccharide matrix with the maximum content of tetracycline (6.68 wt %). The study of the antimicrobial activity of obtained compounds against S. aureus, B. cereus, E. coli showed no decrease in the antimicrobial effect compared to source tetracycline. Thus, the future research towards the new design compounds based on studied complexes could make contribution to a new generation of drugs based on pectin biopolymers.

To study drug resistance & biofilm production in gram negative isolates from clinical samples

Biofilms are groups of microorganism encased in a matrix of extracellular polysaccharide (slime), called polysaccharide intercellular adhesion (PIA). Bacteria commonly involved include , , , and . The present study was performed to identify antibiotic resistance pattern & their ability to form biofilm in gram negative clinical isolates. All clinical samples received in laboratory for microbial culture during study period of 12 months (2017 to 2018) were included in this study Antibiotic susceptibility testing, ESBL & MBL detection was done for clinical isolates. Biofilm productions were determined by Congo red agar method, Christenson’s Test Tube method and Tissue culture plate method. 327 gram negative isolates were detected. Maximum were (32.72%) followed by (28.44%), (16.51%), (16.51%), Citrobacter species (3.97%). Maximum isolates showed resistance to ampicillin (93.27%) followed by amoxiclave (87.46%), ceftazidime (74%). Out of 327 GNB isolates, biofilm produced by 64 (19.57%) isolates by Tissue culture plate (TCP) method, 38(11.62%) by Congo red agar (CRA) method and 23 (7.03%) by Tube method. Maximum biofilm were detected in (24.29%). There is increase prevalence of multidrug resistant& biofilm forming bacteria. The routine monitoring of multidrug resistance pattern & biofilm detection can be recommended in clinical laboratories to guide proper antibiotic treatment.

Biomimetic Adsorptive Composites for Redox Remediation of Organic Pollutants

Conductive hydrogels have gained interest as responsive materials for pollutant sensing and degradation in a variety of applications such as wastewater and soil remediation. There has been a significant increase in both commercial and domestic wastewater, which is output into ground sources, acting as a leading contaminant for surrounding communities. Specifically, cationic organic textile dyes such as methylene blue, methyl red, and methyl violet which are known monoamine oxidase inhibitors are prevalent pollutants. To improve remediation, this work employs a biopolymeric (i.e. polysaccharide) matrix to aid in non-covalent adsorption of pollutants to the network. Additionally, modification of the polysaccharide backbone with a conductive polymer can promote electron transfer throughout the matrix. This work employs the photoinitiation of a metal-polysaccharide complex to directly polymerize polyaniline (PANI) on the polysaccharide backbone. The PANI-functionalized composite can be utilized as a reducing substrate for the adsorptive redox remediation of the organic pollutants that occur in contaminated soils or water supplies.

Inhibition of Staphylococcus aureus biofilm formation by gurmarin, a plant-derived cyclic peptide.

Staphylococcus aureus (Sa) is an opportunistic pathogen capable of causing various infections ranging from superficial skin infections to life-threatening severe diseases including pneumonia and sepsis. Sa produces biofilms readily on biotic and abiotic surfaces. Biofilm cells are embedded in a protective polysaccharide matrix and show an innate resistance to antibiotics, disinfectants, and clearance by host defenses. Additionally, biofilms serve as a source for systemic dissemination. Moreover, infections associated with biofilms may result in longer hospitalizations, a need for surgery, and may even result in death. Agents that inhibit the formation of biofilms and virulence without affecting bacterial growth to avoid the development of drug resistance could be useful for therapeutic purposes. In this regard, we identified and purified a small cyclic peptide, gurmarin, from a plant source that inhibited the formation of Sa biofilm under in vitro growth conditions without affecting the viability of the bacterium. The purified peptide showed a predicted molecular size of ~4.2 kDa on SDS-PAGE. Transcriptomic analysis of Sa biofilm treated with peptide showed 161 differentially affected genes at a 2-fold change, and some of them include upregulation of genes involved in oxidoreductases and downregulation of genes involved in transferases and hydrolases. To determine the inhibitory effect of the peptide against Sa biofilm formation and virulence in vivo, we used a rat-implant biofilm model. Sa infected implants with or without peptide were placed under the neck skin of rats for seven days. Implants treated with peptide showed a reduction of CFU and lack of edema and sepsis when compared to that of control animals without peptide. Taken together, gurmarin peptide blocks Sa biofilm formation in vitro and in vivo and can be further developed for therapeutic use.

Together is better: poly(tannic acid) nanorods functionalized polysaccharide hydrogels for diabetic wound healing

Polysaccharide hydrogel dressings are strong candidates for wound healing due to their low-cost, adsorbable, biodegradable, and biocompatible features. However, they may have some drawbacks, such as static properties, weak mechanics, and the inability to fully meet the requirements of the different phases of wound repair. Enhanced functionality achieved by incorporating nanomaterials into traditional polysaccharide networks is an effective way to address these challenges. Herein, an all-in-one hydrogel dressing (OQP2) that possessed hemostasis , antibacterial, reactive oxygen species scavenging, and angiogenic properties was readily synthesized by introducing poly(tannic acid) nanorods into a polysaccharide matrix comprising oxidized β-glucan and quaternary ammonium chitosan. As expected, the OQP2 can accelerate wound healing in diabetic rat models. This study offers a convenient and facile one-pot strategy to construct multifunctional polysaccharide hydrogel dressings for treating diabetic wounds. • A hydrogel (OQP) dressing was fabricated for accelerating wound healing. • OQP composed of poly(tannic acid) nanorods and a polysaccharide matrix. • OQP possessed convenient, efficient, economical, injectable, and safe properties. • OQP can adsorb wound exudates, reduce inflammation, and guide tissue regeneration.

Biofilm formation and its regulation by extracellular appendages in Pseudomonas aeruginosa

Pseudomonas aeruginosa is an infectious rod like bacterium which is equipped with a unique quorum-sensing system to sense the surrounding environment and communicate with bacterial cells in vicinity through excreting small molecules, called autoinducers. Quorum sensing system and autoinducer production are cellular density dependent mechanisms which are responsible for cell-cell signalling and regulating biological processes in this bacterium. P. aeruginosa is equipped with an arsenal of virulence factors and tools to protect it from toxins and host immune response which facilitate its survival in a wide range of habitats and environments. The most important virulence factor is biofilm which comprises of sessile community of bacteria covered with a matrix of polysaccharides and extracellular proteins offering enhanced resistance to antibiotics and host immune system. P. aeruginosa produces biofilms at a variety of infection sites in patients, on medical instruments and medical tools inside the patient body. It is very hard to eradicate and inhibit the formation of biofilms in immunocompromised patients. In this article, we described the stages of biofilm formation along with the role of various genetic and biochemical factors required for its formation. Special emphasis was given to extra-cellular appendages (flagella, pili and fimbriae) for their role in attachment of P. aeruginosa to the semi-solid serfaces and converting motile bacteria to sessile mode of life (biofilm). Moreover, polysaccharide matix formation and its resistance towards antibiotics is discussed. This review article can help in devising gene therapy strategies against biofilm formation and its eradication in nosocomial infections caused by drug resistant bacteria.

Chemical characterization of the introduced red alga Polyopes lancifolius (Halymeniales, Rhodophyta) from the Gulf of Morbihan, France

ABSTRACT Polyopes lancifolius is an introduced species of Halymeniales (Rhodophyta) from Asia, discovered on the North Atlantic coast in 2008. In this study, a first biochemical description of the species from the Gulf of Morbihan (France) is presented. The overall biochemical analysis of the algal raw material showed levels of neutral sugars (25.14% dw), proteins (15.00% dw), lipids (2.30% dw) and ash (12.64% dw) similar to those observed in species of the genera Grateloupia and Halymenia (Halymeniales). The major mycosporin-like amino acids were the shinorine, palythine and porphyra-334. Matrix polysaccharides represented 62% of the alga. The extract contained a high level of 3,6-anhydrogalactose (44.26%) and a low level of sulphates (10.2%). Uronic acids were also identified in the polysaccharide extract (13.03% dw). Galactose (64.54%) and glucose (27.92%) were the two main monosaccharides. Physico-chemical analyses showed that P. lancifolius contained kappa-carrageenan. The chemical and spectrometry results suggested the presence of agarocolloids and glucans with a high diversity of compounds in the extract. The characterization of the polysaccharide families requires future study.

Evaluation of Polysaccharide-Peptide Conjugates Containing the RGD Motif for Potential Use in Muscle Tissue Regeneration.

New scaffold materials composed of biodegradable components are of great interest in regenerative medicine. These materials should be: stable, nontoxic, and biodegrade slowly and steadily, allowing the stable release of biodegradable and biologically active substances. We analyzed peptide-polysaccharide conjugates derived from peptides containing RGD motif (H-RGDS-OH (1), H-GRGDS-NH2 (2), and cyclo(RGDfC) (3)) and polysaccharides as scaffolds to select the most appropriate biomaterials for application in regenerative medicine. Based on the results of MTT and Ki-67 assays, we can state that the conjugates containing calcium alginate and the ternary nonwoven material were the most supportive of muscle tissue regeneration. Scanning electron microscopy imaging and light microscopy studies with hematoxylin–eosin staining showed that C2C12 cells were able to interact with the tested peptide–polysaccharide conjugates. The release factor (Q) varied depending on both the peptide and the structure of the polysaccharide matrix. LDH, Alamarblue®, Ki-67, and cell cycle assays indicated that peptides 1 and 2 were characterized by the best biological properties. Conjugates containing chitosan and the ternary polysaccharide nonwoven with peptide 1 exhibited very high antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae. Overall, the results of the study suggested that polysaccharide conjugates with peptides 1 and 2 can be potentially used in regenerative medicine.

Controlling Superselectivity of Multivalent Interactions with Cofactors and Competitors.

Moieties that compete with multivalent interactions or act as cofactors are common in living systems, but their effect on multivalent binding remains poorly understood. We derive a theoretical model that shows how the superselectivity of multivalent interactions is modulated by the presence of cofactors or competitors. We find that the role of these participating moieties can be fully captured by a simple rescaling of the affinity constant of the individual ligand–receptor bonds. Theoretical predictions are supported by experimental data of the membrane repair protein annexin A5 binding to anionic lipid membranes in the presence of Ca2+ cofactors and of the extracellular matrix polysaccharide hyaluronan (HA) binding to CD44 cell surface receptors in the presence of HA oligosaccharide competitors. The obtained findings should facilitate understanding of multivalent recognition in biological systems and open new routes for fine-tuning the selectivity of multivalent nanoprobes in medicinal chemistry.

Kin Discrimination Modifies Strain Distribution, Spatial Segregation, and Incorporation of Extracellular Matrix Polysaccharide Mutants of Bacillus subtilis Strains into Mixed Floating Biofilms.

ABSTRACTMicroorganisms in nature form multicellular groups called biofilms. In biofilms, bacteria embedded in the extracellular matrix (ECM) interact intensely due to their proximity. Most studies have investigated genetically homogeneous biofilms, leaving a gap in knowledge on genetically heterogeneous biofilms. Recent insights show that a Gram-positive model bacterium, Bacillus subtilis, discriminates between strains of high (kin) and low (nonkin) genetic similarity, reflected in merging (kin) and boundaries (nonkin) between swarms. However, it is unclear how kinship between interacting strains affects their fitness, the genotype assortment, and incorporation of the mutant lacking the main structural ECM polysaccharide (EpsA-O) into floating biofilms (pellicles). We cultivated Bacillus subtilis strains as mixtures of isogenic, kin, and nonkin strain combinations in the biofilm-promoting minimal medium under static conditions, allowing them to form pellicles. We show that in nonkin pellicles, the dominant strain strongly reduced the frequency of the other strain. Segregation of nonkin mixtures in pellicles increased and invasion of nonkin EpsA-O-deficient mutants into pellicles decreased compared to kin and isogenic floating biofilms. Kin and isogenic strains had comparable relative frequencies in pellicles and showed more homogenous cell mixing. Overall, our results emphasize kin discrimination as a social behavior that shapes strain distribution, spatial segregation, and ECM mutant ability to incorporate into genetically heterogenous biofilms of B. subtilis.IMPORTANCE Biofilm communities have beneficial and harmful effects on human societies in natural, medical, and industrial environments. Bacillus subtilis is a biotechnologically important bacterium that serves as a model for studying biofilms. Recent studies have shown that this species engages in kin discriminatory behavior during swarming, which may have implications for community assembly, thus being of fundamental importance. Effects of kin discrimination on fitness, genotype segregation, and success of extracellular matrix (ECM) polysaccharide (EpsA-O) mutant invasion into biofilms are not well understood. We provide evidence that kin discrimination depends on the antagonism of the dominant strain against nonkin by using environmental strains with determined kin types and integrated fluorescent reporters. Moreover, this antagonism has important implications for genotype segregation and for when the bacteria are mixed with ECM producers. The work advances the understanding of kin-discrimination-dependent bacterial sociality in biofilms and its role in the assembly of multicellular groups.

Whole genome duplication of wild-type and CINNAMYL ALCOHOL DEHYDROGENASE1-downregulated hybrid poplar reduces biomass yield and causes a brittle apex phenotype in field-grown wild types.

The potential of whole genome duplication to increase plant biomass yield is well-known. In Arabidopsis tetraploids, an increase in biomass yield was accompanied by a reduction in lignin content and, as a result, a higher saccharification efficiency was achieved compared with diploid controls. Here, we evaluated whether the results obtained in Arabidopsis could be translated into poplar and whether the enhanced saccharification yield upon alkaline pretreatment of hairpin-downregulated CINNAMYL ALCOHOL DEHYDROGENASE1 (hpCAD) transgenic poplar could be further improved upon a whole genome duplication. Using a colchicine treatment, wild-type (WT) Populus tremula x P. alba cv. INRA 717-1B4, a commonly used model clone in tree biotechnology research, and hpCAD tetraploids were generated and grown in the greenhouse. In parallel, WT tetraploid poplars were grown in the field. In contrast to Arabidopsis, a whole genome duplication of poplar had a negative impact on the biomass yield of both greenhouse- and field-grown trees. Strikingly, field-grown WT tetraploids developed a brittle apex phenotype, i.e., their tip broke off just below the apex. In addition, the chromosome doubling altered the biomass composition of field-grown, but not of greenhouse-grown tetraploid poplars. More specifically, the lignin content of field-grown tetraploid poplars was increased at the expense of matrix polysaccharides. This increase in lignin deposition in biomass is likely the cause of the observed brittle apex phenotype, though no major differences in stem anatomy or in mechanical properties could be found between di- and tetraploid WT poplars grown in the field. Finally, without biomass pretreatment, the saccharification efficiency of greenhouse- and field-grown WT diploids was not different from that of tetraploids, whereas that of greenhouse-grown hpCAD tetraploids was higher than that of greenhouse-grown diploids. Upon alkaline pretreatment, the saccharification yield of diploids was similar to that of tetraploids for all genotypes and growth conditions tested. This study showed that a whole genome duplication in hybrid WT and hpCAD poplar did neither result in further improvements in biomass yield, nor in improved biomass composition and, hence, saccharification performance.

Evolution of nacre- and prisms-related shell matrix proteins in the pen shell, Atrina pectinata

The molluscan shell is a good model for understanding the mechanisms underlying biomineralization. It is composed of calcium carbonate crystals and many types of organic molecules, such as the matrix proteins, polysaccharides, and lipids. The pen shell Atrina pectinata (Pterioida, Pinnidae) has two shell microstructures: an outer prismatic layer and an inner nacreous layer. Similar microstructures are well known in pearl oysters (Pteriidae), such as Pinctada fucata, and many kinds of shell matrix proteins (SMPs) have been identified from their shells. However, the members of SMPs that consist of the nacreous and prismatic layers of Pinnidae bivalves remain unclear. In this study, we identified 114 SMPs in the nacreous and prismatic layers of A. pectinata, of which only seven were found in both microstructures. 54 of them were found to bind calcium carbonate. Comparative analysis of nine molluscan shell proteomes showed that 69 of 114 SMPs of A. pectinata were found to have sequential similarity with at least one or more SMPs of other molluscan species. For instance, nacrein, tyrosinase, Pif/BMSP-like, chitinase (CN), chitin-binding proteins, CD109, and Kunitz-type serine proteinase inhibitors are widely shared among bivalves and gastropods. Our results provide new insights for understanding the complex evolution of SMPs related to nacreous and prismatic layer formation in the pteriomorph bivalves.

The trans-Golgi-localized protein BICAT3 regulates manganese allocation and matrix polysaccharide biosynthesis.

Manganese (Mn2+) is essential for a diversity of processes, including photosynthetic water splitting and the transfer of glycosyl moieties. Various Golgi-localized glycosyltransferases that mediate cell wall matrix polysaccharide biosynthesis are Mn2+ dependent, but the supply of these enzymes with Mn2+ is not well understood. Here, we show that the BIVALENT CATION TRANSPORTER 3 (BICAT3) localizes specifically to trans-cisternae of the Golgi. In agreement with a role in Mn2+ and Ca2+ homeostasis, BICAT3 rescued yeast (Saccharomyces cerevisiae) mutants defective in their translocation. Arabidopsis (Arabidopsis thaliana) knockout mutants of BICAT3 were sensitive to low Mn2+ and high Ca2+ availability and showed altered accumulation of these cations. Despite reduced cell expansion and leaf size in Mn2+-deficient bicat3 mutants, their photosynthesis was improved, accompanied by an increased Mn content of chloroplasts. Growth defects of bicat3 corresponded with an impaired glycosidic composition of matrix polysaccharides synthesized in the trans-Golgi. In addition to the vegetative growth defects, pollen tube growth of bicat3 was heterogeneously aberrant. This was associated with a severely reduced and similarly heterogeneous pectin deposition and caused diminished seed set and silique length. Double mutant analyses demonstrated that the physiological relevance of BICAT3 is distinct from that of ER-TYPE CA2+-ATPASE 3, a Golgi-localized Mn2+/Ca2+-ATPase. Collectively, BICAT3 is a principal Mn2+ transporter in the trans-Golgi whose activity is critical for specific glycosylation reactions in this organelle and for the allocation of Mn2+ between Golgi apparatus and chloroplasts.

The regulation of the cell wall by glycosylphosphatidylinositol-anchored proteins in Arabidopsis.

A polysaccharides-based cell wall covers the plant cell, shaping it and protecting it from the harsh environment. Cellulose microfibrils constitute the cell wall backbone and are embedded in a matrix of pectic and hemicellulosic polysaccharides and glycoproteins. Various environmental and developmental cues can regulate the plant cell wall, and diverse glycosylphosphatidylinositol (GPI)-anchored proteins participate in these regulations. GPI is a common lipid modification on eukaryotic proteins, which covalently tethers the proteins to the membrane lipid bilayer. Catalyzed by a series of enzymic complexes, protein precursors are post-translationally modified at their hydrophobic carboxyl-terminus in the endomembrane system and anchored to the lipid bilayer through an oligosaccharidic GPI modification. Ultimately, mature proteins reach the plasma membrane via the secretory pathway facing toward the apoplast and cell wall in plants. In Arabidopsis, more than three hundred GPI-anchored proteins (GPI-APs) have been predicted, and many are reported to be involved in diverse regulations of the cell wall. In this review, we summarize GPI-APs involved in cell wall regulation. GPI-APs are proposed to act as structural components of the cell wall, organize cellulose microfibrils at the cell surface, and during cell wall integrity signaling transduction. Besides regulating protein trafficking, the GPI modification is potentially governed by a GPI shedding system that cleaves and releases the GPI-anchored proteins from the plasma membrane into the cell wall.

Cryostructuring of Polymeric Systems: 62 Preparation and Characterization of Alginate/Chondroitin Sulfate Cryostructurates Loaded with Antimicrobial Substances.

Targeted drug release is a significant research focus in the development of drug delivery systems and involves a biocompatible polymeric carrier and certain medicines. Cryostructuring is a suitable approach for the preparation of efficient macroporous carriers for such drug delivery systems. In the current study, the cryogenically structured carriers based on alginate/chondroitin sulfate mixtures were prepared and their physicochemical properties and their ability to absorb/release the bactericides were evaluated. The swelling parameters of the polysaccharide matrix, the amount of the tightly bound water in the polymer and the sulfur content were measured. In addition, FTIR and UV spectroscopy, optical and scanning microscopy, as well as a standard disk diffusion method for determining antibacterial activity were used. It was shown that alginate/chondroitin sulfate concentration and their ratios were significant factors influencing the swelling properties and the porosity of the resultant cryostructurates. It was demonstrated that the presence of chondroitin sulfate in the composition of a polymeric matrix slowed down the release of the aminoglycoside antibiotic gentamicin. In the case of the NH2-free bactericide, dioxidine, the release was almost independent of the presence of chondroitin sulfate. This trend was also registered for the antibacterial activity tests against the Escherichia coli bacteria, when examining the drug-loaded biopolymeric carriers.

Bacterial Cellulose/Tomato Puree Edible Films as Moisture Barrier Structures in Multicomponent Foods.

Edible films have been studied mainly as primary packaging materials, but they may be used as barrier layers between food components, e.g., by reducing the moisture migration between components with contrasting water activities. Since edible films are part of the food itself, components adding sensory appeal (e.g., fruit purees) are usually desirable. The objective of this study was to develop a film to be applied as a moisture barrier between nachos and guacamole. Ten film formulations were prepared according to a simplex centroid design with three components—a polysaccharide matrix (consisting of a 5:1 mixture of bacterial cellulose—BC—and carboxymethyl cellulose), tomato puree (for sensory appeal), and palm olein (to reduce hydrophilicity)—and produced by bench casting. The film with the highest palm olein content (20%) presented the lowest water vapor permeability, and its formulation was used to produce a film by continuous casting. The film was applied as a layer between nachos and guacamole, and presented to 80 panelists. The film-containing snack was preferred and considered as crispier when compared to the snack without the film, suggesting that the film was effective in reducing the moisture migration from the moist guacamole to the crispy nachos.