Assembly Of Polysaccharide Research Articles

Stepwisely Assembled Multicomponent Fiber with High Water Content and Superior Mechanical Properties for Artificial Ligament.

The ligament, which connects bones at the joints, has both high water content and excellent mechanical properties in living organisms. However, it is still challenging to fabricate fibrous materials that possess high water content and ligament-like mechanical characteristics simultaneously. Herein, the design and preparation of a ligament-mimicking multicomponent fiber is reported through stepwise assembly of polysaccharide, calcium, and dopamine. In simulated body fluid, the resulting fiber has a water content of 40wt%, while demonstrating strength of ≈120MPa, a Young's modulus of ≈3GPa, and a toughness of ≈25MJm-3. Additionally, the multicomponent fiber exhibits excellent creep and fatigue resistance, as well as biocompatibility to support cell growth in vitro. These findings suggest that the fiber has potential for engineering high-performance artificial ligament.

The mechanistic study of using microparticle Al2O3 to promote the production of exopolysaccharides in submerged fermentation of Antrodia cinnamomea

In this study, a notable increase of 136.9% in the production of exopolysaccharides (EPS) was observed during the submerged fermentation of Antrodia cinnamomea when microparticle (4 g/L of Al2O3) was applied. By evaluating the activities of key enzymes involved in EPS synthesis in A. cinnamomea, it was found that the addition of Al2O3 enhanced the activities of phosphoglycerate mutase (PGM), UDP-glucose pyrophosphorylase (UGP), and GDP-mannose pyrophosphorylase (GMPPB). To further elucidate the mechanism through which Al2O3 enhances the production of EPS in A. cinnamomea, a transcriptomic analysis was conducted to compare the gene expression levels. The results showed that there was a significant up-regulation of genes associated with the synthesis and assembly of polysaccharide repeating units, as well as genes responsible for the regulation of ABC transporter complex enzymes. To verify the above hypothesis, the ABC transporter inhibitor MK-571 sodium salt was added to the fermentation broth of A. cinnamomea. The study demonstrated that when the ABC transporter was inhibited, the yield of EPS was significantly reduced, which further confirmed that the addition of Al2O3 could improve the activity of ABC transporter and promote the production of EPS in submerged fermentation of A. cinnamomea.

The assembly of polysaccharide ZIF-8-based foam for efficient adsorptive removal of PEDCs from environmental water

ZIF-8 is a type of porous coordination metal-organic frameworks (MOFs) material with excellent adsorption properties. However, the inevitable acid-base sensitivity and low plasticity of ZIF-8 impede its application to the field of compound adsorption and separation. Here, a novel reusable monolithic MOFs foam material, polysaccharides (CMC & chitin) gels zeolitic imidazolate frameworks (PC-ZIF-8), has been developed to effectively adsorb five Phenolic Endocrine Disrupting Chemicals (PEDCs) from environmental water. In this study, the forming strategy of a continuous phase change sol-gel MOFs material was designed. The carboxymethyl cellulose and chitin hydrosol were used as the self-assembly medium for in-situ synthesizing sol-type MOFs by a one-step method. Several favorable characteristics of PC-ZIF-8 have been confirmed, including large surface area (619.47 m2/g), low density (<0.085 g/cm3), high ZIF-8 loading rate (>80%, wt%), high structural strength, high acid, and alkali tolerance, and easy recyclability. The adsorption efficiency of PC-ZIF-8 for 5 BPs in water is 92.97%− 99.12%, and the maximum adsorption capacity is 120.1–172.9 mg/g. After simple regeneration treatment, PC-ZIF-8 has been recycled 5 times, and the overall recovery rate still remains above 80.0%. The results of this study indicate that PC-ZIF-8 is a reliable adsorbent for BPs in environmental water purification.

Metabolic cross-feeding structures the assembly of polysaccharide degrading communities.

Metabolic processes that fuel the growth of heterotrophic microbial communities are initiated by specialized biopolymer degraders that decompose complex forms of organic matter. It is unclear, however, to what extent degraders structure the downstream assembly of the community that follows polymer breakdown. Investigating a model marine microbial community that degrades chitin, we show that chitinases secreted by different degraders produce oligomers of specific chain lengths that not only select for specialized consumers but also influence the metabolites secreted by these consumers into a shared resource pool. Each species participating in the breakdown cascade exhibits unique hierarchical preferences for substrates, which underlies the sequential colonization of metabolically distinct groups as resource availability changes over time. By identifying the metabolic underpinnings of microbial community assembly, we reveal a hierarchical cross-feeding structure that allows biopolymer degraders to shape the dynamics of community assembly.

Wza gene knockout decreases Acinetobacter baumannii virulence and affects Wzy-dependent capsular polysaccharide synthesis

ABSTRACT To investigate the virulence of capsular polysaccharide export protein (Wza) in carbapenem-resistant Acinetobacter baumannii and its effect on capsule formation. wza gene knockout and complementation strains were constructed, and changes in bacterial virulence were observed using in vitro adhesion, antiserum complement killing, anti-oxidation experiments, and infections in Galleria mellonella and mice. The effect of wza knockout on the genes wzb and wzc and wzi were assessed by RT-PCR. We successfully constructed wza knockout and complementation strains. Compared with wild-type (WT) strains, wza knockout strains displayed lower adhesion to A549 cells (p = 0.044), lower antiserum complement killing ability (p = 0.001), and lower mortality of G. mellonella (p = 0.010) and mice (p = 0.033). Expression levels of wzb, wzc and wzi were decreased in wza knockout strains. The antioxidant capacity of Wza knockout bacteria was only slightly decreased. Complementation of the wza gene returned the adhesion ability, antiserum complement killing ability, and mortality of G. mellonella and mice to WT levels. Expression of wzb, wzc and wzi was also returned to WT levels following wza complementation. The results clearly demonstrate that Wza is toxic. Wza affects the expression of other proteins of the Wzy capsule polysaccharide synthesis pathway, which affects the assembly, export, and extracellular fixation of capsular polysaccharide, resulting in synergistic effects that decrease bacterial virulence.

A novel ultra‐low energy reverse osmosis membrane modified by chitosan with glutaraldehyde crosslinking

ABSTRACTThe energy consumption of reverse osmosis (RO) has declined significantly since inception and to further decrease the energy consumption is a challenging task. The present article demonstrates the novel method to increase the membrane productivity and reduce energy consumption of desalination. Thin film composite RO (TFC RO) membrane was subjected to 2000 mg/L sodium hypochlorite for 1 h followed by varying concentrations of chitosan and glutaraldehyde for 1 h each to make a hydrophilic supra‐molecular assembly of linear polysaccharide over the polyamide layer. RO membrane exposed to 1000 mg/L chitosan and glutaraldehyde each reported 180% increase in water‐flux with about 2.7% increase in divalent ion rejection as compared to virgin TFC RO membrane. The superior performance of the membrane was explained by increased hydrophilicity as shown by decline in contact angle from 46.37° to 29.87°, increase in surface area ratio from atomic force microscope image analysis, and modification in chemical structure of polyamide from attenuated total reflectance Fourier transform infrared spectroscopy. It was further investigated that curing of glutaraldehyde treated membrane resulted in decreased water‐flux because of increase in crosslink density. Thus, an ultra‐low energy RO process can be developed based on polyamide–chitosan–glutaraldehyde membrane. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45971.

Layer-by-layer assembly of multilayer polysaccharide coated magnetic nanoparticles for the selective enrichment of glycopeptides

Magnetic nanoparticles (MNPs) coated with multilayer polysaccharide shells have been fabricated using a layer-by-layer approach via the alternate deposition of hyaluronan (HA) and chitosan (CS) onto the surface, and the hydrophilic materials were utilized for effective and selective enrichment of glycopeptides in biological samples.

RppA, a transducer homologue, and MmrA, a multidrug transporter homologue, are involved in the biogenesis and/or assembly of polysaccharide in Myxococcus xanthus.

Myxococcus xanthus cells move by gliding, and form multicellular fruiting bodies under conditions of starvation. The authors cloned a gene, designated rppA (for receptor for polysaccharide production), which encodes a methyl-accepting protein homologous to the chemotaxis transducers in eubacteria. The rppA gene was co-transcribed with mmrA, a gene homologous to various multidrug transporter genes. The rppA or mmrA single mutants showed almost identical phenotypes to the wild-type strain; however, the rppA-mmrA double mutant exhibited reduced colony expansion, cell-cell agglutination and cellular reversal frequency. The double-mutant cells also showed less binding to Congo red, which mainly binds to fibril polysaccharide, than wild-type cells. Analysis of total polysaccharide in stationary-phase cells demonstrated that in the double mutant, polysaccharide levels were decreased by about 30 % as compared with the wild-type strain. These results indicated that RppA and MmrA play a role in the biogenesis and/or assembly of polysaccharide, and the phenotypes of the double mutant may be due to the reduction in fibril polysaccharide.

Phosphorylation of Wzc, a Tyrosine Autokinase, Is Essential for Assembly of Group 1 Capsular Polysaccharides in Escherichia coli

Wzc proteins are tyrosine autokinases. They are found in some important bacterial pathogens of humans and livestock as well as plant-associated bacteria, and are often encoded within gene clusters determining synthesis and assembly of capsular and extracellular polysaccharides. Autophosphorylation of Wzc(cps) is essential for assembly of the serotype K30 group 1 capsule in Escherichia coli O9a:K30, although a genetically unlinked Wzc(cps)-homologue (Etk) can also participate with low efficiency. While autophosphorylation of Wzc(cps) is required for assembly of high molecular weight K30 capsular polysaccharide, it is not essential for either the synthesis of the K30 repeat units or for activity of the K30 polymerase enzyme. Paradoxically, the cognate phosphotyrosine protein phosphatase for Wzc(cps), Wzb(cps), is also required for capsule expression. The tyrosine-rich domain at the C terminus of Wzc(cps) was identified as the site of phosphorylation and autophosphorylation of Wzc requires a functional Walker A motif. Intermolecular transphosphorylation of Wzc(cps) was detected in strains expressing a combination of mutant Wzc(cps) derivatives. The N- and C-terminal domains of Wzc(cps) were expressed independently to mimic the situation found naturally in Gram-positive bacteria. In this format, both domains were required for phosphorylation of the Wzc(cps) C terminus, and for capsule assembly. Regulation by a post-translational phosphorylation event represents a new dimension in the assembly of bacterial cell-surface polysaccharides.

Linkage of genes essential for synthesis of a polysaccharide capsule in Sphingomonas strain S88

Several structurally related capsular polysaccharides that are secreted by members of the genus Sphingomonas are being developed as aqueous rheological control agents for diverse industrial and food applications. They include gellan (S-60), welan (S-130), rhamsan (S-194), S-657, S-88, S-198, S-7, and NW-11. We refer to these polysaccharides as sphingans, after the genus name. This paper characterizes the first gene cluster isolated from a Sphingomonas species (S88) that is required for capsule synthesis. Overlapping DNA segments which spanned about 50 kbp of S88 DNA restored the synthesis of sphingan S-88 in capsule-negative mutants. The mutations were mapped into functional complementation groups, and the contiguous nucleotide sequence for the 29-kbp cluster was determined. The genetic complementation map and the DNA sequences were interpreted as an extended multicistronic locus containing genes essential for the assembly and secretion of polysaccharide S-88. Many of the deduced amino acid sequences were similar to gene products from other polysaccharide-secreting bacteria such as Rhizobium meliloti (succinoglycan), Xanthomonas campestris (xanthan gum), and Salmonella enterica (O antigen). The S88 locus contained a four-gene operon for the biosynthesis of dTDP-L-rhamnose, an essential precursor for the sphingans. Unexpectedly, there were also two genes for secretion of a lytic or toxin-like protein nested within the polysaccharide cluster. The conservation and linkage of genes that code for a defensive capsule and genes for secretion of an offensive lysin or toxin suggest a heretofore unknown pathogenic life history for Sphingomonas strain S88.