Showing papers on "Chitin published in 2014"
TL;DR: The data suggest that AtLYK5 is the primary receptor for chitin, forming a chitIn inducible complex with AtCERK1 to induce plant immunity.
Abstract: Chitin is a fungal microbe-associated molecular pattern recognized in Arabidopsis by a lysin motif receptor kinase (LYK), AtCERK1. Previous research suggested that AtCERK1 is the major chitin receptor and mediates chitin-induced signaling through homodimerization and phosphorylation. However, the reported chitin binding affinity of AtCERK1 is quite low, suggesting another receptor with high chitin binding affinity might be present. Here, we propose that AtLYK5 is the primary chitin receptor in Arabidopsis. Mutations in AtLYK5 resulted in a significant reduction in chitin response. However, AtLYK5 shares overlapping function with AtLYK4 and, therefore, Atlyk4/Atlyk5-2 double mutants show a complete loss of chitin response. AtLYK5 interacts with AtCERK1 in a chitin-dependent manner. Chitin binding to AtLYK5 is indispensable for chitin-induced AtCERK1 phosphorylation. AtLYK5 binds chitin at a much higher affinity than AtCERK1. The data suggest that AtLYK5 is the primary receptor for chitin, forming a chitin inducible complex with AtCERK1 to induce plant immunity.
433 citations
TL;DR: This review article discusses the most recent progress in the preparation and application of chitin and chitosan based nanofibrous materials in biomedical fields.
Abstract: Over the past several decades, we have witnessed significant progress in chitosan and chitin based nanostructured materials. The nanofibers from chitin and chitosan with appealing physical and biological features have attracted intense attention due to their excellent biological properties related to biodegradability, biocompatibility, antibacterial activity, low immunogenicity and wound healing capacity. Various methods, such as electrospinning, self-assembly, phase separation, mechanical treatment, printing, ultrasonication and chemical treatment were employed to prepare chitin and chitosan nanofibers. These nanofibrous materials have tremendous potential to be used as drug delivery systems, tissue engineering scaffolds, wound dressing materials, antimicrobial agents, and biosensors. This review article discusses the most recent progress in the preparation and application of chitin and chitosan based nanofibrous materials in biomedical fields.
299 citations
TL;DR: Chitin and chitosan characteristics were depending upon the chitin source, and α-chitins were more crystalline polymorph than β-chITin.
281 citations
TL;DR: This review focuses on the preparation and biological activities of chitin, chitosan, COS, and their derivatives, and the greater solubility and low viscosity of COS have attracted the interest of many researchers to utilize COS and their derivative for various biomedical applications.
Abstract: Chitin is a natural polysaccharide of major importance. This biopolymer is synthesized by an enormous number of living organisms; considering the amount of chitin produced annually in the world, it is the most abundant polymer after cellulose. The most important derivative of chitin is chitosan, obtained by partial deacetylation of chitin under alkaline conditions or by enzymatic hydrolysis. Chitin and chitosan are known to have important functional activities but poor solubility makes them difficult to use in food and biomedicinal applications. Chitooligosaccharides (COS) are the degraded products of chitosan or chitin prepared by enzymatic or chemical hydrolysis of chitosan. The greater solubility and low viscosity of COS have attracted the interest of many researchers to utilize COS and their derivatives for various biomedical applications. In light of the recent interest in the biomedical applications of chitin, chitosan, and their derivatives, this review focuses on the preparation and biological activities of chitin, chitosan, COS, and their derivatives.
261 citations
TL;DR: This chapter presents an overview of the antioxidant activity of chitin, chitosan, and their derivatives with the potential utilization in the food and pharmaceutical industries.
Abstract: Chitin, chitosan, and their derivatives are considered to promote diverse activities, including antioxidant, antihypertensive, anti-inflammatory, anticoagulant, antitumor and anticancer, antimicrobial, hypocholesterolemic, and antidiabetic effects, one of the most crucial of which is the antioxidant effect. By modulating and improving physiological functions, chitin, chitosan, and their derivatives may provide novel therapeutic applications for the prevention or treatment of chronic diseases. Antioxidant activity of chitin, chitosan, and their derivatives can be attributed to in vitro and in vivo free radical-scavenging activities. Antioxidant effect of chitin, chitosan, and their derivatives may be used as functional ingredients in food formulations to promote consumer health and to improve the shelf life of food products. This chapter presents an overview of the antioxidant activity of chitin, chitosan, and their derivatives with the potential utilization in the food and pharmaceutical industries.
228 citations
TL;DR: Results indicate that NCU08746 and homologs are starch-active PMOs, supporting the existence of a PMO superfamily with a much broader range of substrates and providing an expanded perspective on studies of starch metabolism and may have potential in the food and starch-based biofuel industries.
Abstract: The recently discovered fungal and bacterial polysaccharide monooxygenases (PMOs) are capable of oxidatively cleaving chitin, cellulose, and hemicelluloses that contain β(1→4) linkages between glucose or substituted glucose units. They are also known collectively as lytic PMOs, or LPMOs, and individually as AA9 (formerly GH61), AA10 (formerly CBM33), and AA11 enzymes. PMOs share several conserved features, including a monocopper center coordinated by a bidentate N-terminal histidine residue and another histidine ligand. A bioinformatic analysis using these conserved features suggested several potential new PMO families in the fungus Neurospora crassa that are likely to be active on novel substrates. Herein, we report on NCU08746 that contains a C-terminal starch-binding domain and an N-terminal domain of previously unknown function. Biochemical studies showed that NCU08746 requires copper, oxygen, and a source of electrons to oxidize the C1 position of glycosidic bonds in starch substrates, but not in cellulose or chitin. Starch contains α(1→4) and α(1→6) linkages and exhibits higher order structures compared with chitin and cellulose. Cellobiose dehydrogenase, the biological redox partner of cellulose-active PMOs, can serve as the electron donor for NCU08746. NCU08746 contains one copper atom per protein molecule, which is likely coordinated by two histidine ligands as shown by X-ray absorption spectroscopy and sequence analysis. Results indicate that NCU08746 and homologs are starch-active PMOs, supporting the existence of a PMO superfamily with a much broader range of substrates. Starch-active PMOs provide an expanded perspective on studies of starch metabolism and may have potential in the food and starch-based biofuel industries.
220 citations
TL;DR: Results showed that both chitosans inhibited the growth of most Gram-negative, Gram-positive bacteria and fungi tested and exhibited antioxidant and antitumor activities which was dependent on the molecular weight.
215 citations
TL;DR: It is shown that three immune cell receptors– the mannose receptor, NOD2 and TLR9 recognise chitin and act together to mediate an anti-inflammatory response via secretion of the cytokine IL-10, which may prevent inflammation-based damage during fungal infection and restore immune balance after an infection has been cleared.
Abstract: Chitin is an essential structural polysaccharide of fungal pathogens and parasites, but its role in human immune responses remains largely unknown. It is the second most abundant polysaccharide in nature after cellulose and its derivatives today are widely used for medical and industrial purposes. We analysed the immunological properties of purified chitin particles derived from the opportunistic human fungal pathogen Candida albicans, which led to the selective secretion of the anti-inflammatory cytokine IL-10. We identified NOD2, TLR9 and the mannose receptor as essential fungal chitin-recognition receptors for the induction of this response. Chitin reduced LPS-induced inflammation in vivo and may therefore contribute to the resolution of the immune response once the pathogen has been defeated. Fungal chitin also induced eosinophilia in vivo, underpinning its ability to induce asthma. Polymorphisms in the identified chitin receptors, NOD2 and TLR9, predispose individuals to inflammatory conditions and dysregulated expression of chitinases and chitinase-like binding proteins, whose activity is essential to generate IL-10-inducing fungal chitin particles in vitro, have also been linked to inflammatory conditions and asthma. Chitin recognition is therefore critical for immune homeostasis and is likely to have a significant role in infectious and allergic disease.
214 citations
TL;DR: This work provided a new pathway to prepare the chitin-based materials for highly effective removal of oil from water, showing potential application in the pollutant remediation field.
Abstract: A highly hydrophobic and oleophilic chitin sponge was synthesized, for the first time, via a freeze-dried method and then by using a thermal chemical vapor deposition of methyltrichlorosilane (MTCS) at different relative humidity. Fourier-transform infrared, energy-dispersive X-ray spectra, and scanning electron microscopy confirmed that the silanization occurred on the pore wall surface of the chitin sponge. The MTCS-coated chitin sponge had interconnected open-cell structures with the average pore size from 20 to 50 μm, and the MTCS nanofilaments immobilized on the chitin matrix, leading to the high hydrophobicity, as a result of the existence of a solid/air composite rough surface. Cyclic compression test indicated that the hydrophobic chitin sponges exhibited excellent elasticity and high mechanical durability. The sponges could efficiently collect organics both on the surface and bottom from the water with the highest 58 times of their own weight absorption capacities through the combination of the p...
208 citations
TL;DR: In this article, the authors described the direct conversion of chitin into a nitrogen-containing (N-containing) furan derivative (3A5AF) for the first time under optimized conditions, the yield of 3A5F reached 75% with ca 50% chitIN conversion by using boric acid and alkaline chlorides as additives, and NMP as a solvent.
201 citations
TL;DR: Chitin nanofibers are prepared from the exoskeletons of crabs and prawns, squid pens and mushrooms by a simple mechanical treatment after a series of purification steps, and several modifications to the chitin NF surface are achieved.
Abstract: Chitin nanofibers are prepared from the exoskeletons of crabs and prawns, squid pens and mushrooms by a simple mechanical treatment after a series of purification steps. The nanofibers have fine nanofiber networks with a uniform width of approximately 10 nm. The method used for chitin-nanofiber isolation is also successfully applied to the cell walls of mushrooms. Commercial chitin and chitosan powders are also easily converted into nanofibers by mechanical treatment, since these powders consist of nanofiber aggregates. Grinders and high-pressure waterjet systems are effective for disintegrating chitin into nanofibers. Acidic conditions are the key factor to facilitate mechanical fibrillation. Surface modification is an effective way to change the surface property and to endow nanofiber surface with other properties. Several modifications to the chitin NF surface are achieved, including acetylation, deacetylation, phthaloylation, naphthaloylation, maleylation, chlorination, TEMPO-mediated oxidation, and graft polymerization. Those derivatives and their properties are characterized.
TL;DR: This review synthetizes the state of the art on this domain, but also deals with the assessment of chitosan environmental impact.
TL;DR: Other emerging technologies such as direct degradation of chitin from crustacean shells and microbial cell walls, enzymatic synthesis of COS from small building blocks, and protein engineering technology for chit in-related enzymes have been discussed as the most significant challenge for industrial application.
Abstract: Chitin and chitosan oligosaccharides (COS) have been traditionally obtained by chemical digestion with strong acids. In light of the difficulties associated with these traditional production processes, environmentally compatible and reproducible production alternatives are desirable. Unlike chemical digestion, biodegradation of chitin and chitosan by enzymes or microorganisms does not require the use of toxic chemicals or excessive amounts of wastewater. Enzyme preparations with chitinase, chitosanase, and lysozymeare primarily used to hydrolyze chitin and chitosan. Commercial preparations of cellulase, protease, lipase, and pepsin provide another opportunity for oligosaccharide production. In addition to their hydrolytic activities, the transglycosylation activity of chitinolytic enzymes might be exploited for the synthesis of desired chitin oligomers and their derivatives. Chitin deacetylase is also potentially useful for the preparation of oligosaccharides. Recently, direct production of oligosaccharides from chitin and crab shells by a combination of mechanochemical grinding and enzymatic hydrolysis has been reported. Together with these, other emerging technologies such as direct degradation of chitin from crustacean shells and microbial cell walls, enzymatic synthesis of COS from small building blocks, and protein engineering technology for chitin-related enzymes have been discussed as the most significant challenge for industrial application.
TL;DR: Many studies indicate that chitin and chitosan nanofibers are suitable materials for various biomedical applications, because they have several useful properties such as high specific surface area and high porosity.
Abstract: Chitin (β-(1-4)-poly-N-acetyl-D-glucosamine) is widely distributed in nature and is the second most abundant polysaccharide after cellulose. Chitin occurs in nature as ordered macrofibrils. It is the major structural component in the exoskeleton of crab and shrimp shells and the cell wall of fungi and yeast. As chitin is not readily dissolved in common solvents, it is often converted to its more deacetylated derivative, chitosan. Chitin, chitosan, and its derivatives are widely used in tissue engineering, wound healing, and as functional foods. Recently, easy methods for the preparation of chitin and chitosan nanofibers have been developed, and studies on biomedical applications of chitin and chitosan nanofibers are ongoing. Chitin and chitosan nanofibers are considered to have great potential for various biomedical applications, because they have several useful properties such as high specific surface area and high porosity. This review summarizes methods for the preparation of chitin and chitosan nanofibers. Further, biomedical applications of chitin and chitosan nanofibers in (i) tissue engineering, (ii) wound dressing, (iii) cosmetic and skin health, (iv) stem cell technology, (v) anti-cancer treatments and drug delivery, (vi) anti-inflammatory treatments, and (vii) obesity treatment are summarized. Many studies indicate that chitin and chitosan nanofibers are suitable materials for various biomedical applications.
TL;DR: In this article, a study was undertaken to extract chitin and chitosan by chemical method, and several treatments with acid and alkali were taken into consideration to determine effective concentration for yielding optimum output.
TL;DR: High internal phase emulsions (HIPE) containing up to 96% of internal phase are formed as a gel with a texture that can be modulated from soft to solid gel by adjusting concentration, pH, and ionic strength.
TL;DR: It is demonstrated that the rice LysM receptor-like kinase OsCERK1, a key component of the chitin elicitor signaling pathway, also plays an important role in PGN-triggered immunity in rice.
Abstract: Microbe-associated molecular pattern (MAMP)-triggered immunity plays critical roles in the basal resistance defense response in plants. Chitin and peptidoglycan (PGN) are major molecular patterns for fungi and bacteria, respectively. Two rice (Oryza sativa) lysin motif-containing proteins, OsLYP4 and OsLYP6, function as receptors that sense bacterial PGN and fungal chitin. These membrane receptors, which lack intracellular kinase domains, likely contain another component for transmembrane immune signal transduction. Here, we demonstrate that the rice LysM receptor-like kinase OsCERK1, a key component of the chitin elicitor signaling pathway, also plays an important role in PGN-triggered immunity in rice. Silencing of OsCERK1 suppressed PGN-induced (and chitin-induced) immunity responses, including reactive oxygen species generation, defense gene expression, and callose deposition, indicating that OsCERK1 is essential for both PGN and chitin signaling initiated by OsLYP4 and OsLYP6. OsLYP4 associated with OsLYP6 and the rice chitin receptor chitin oligosaccharide elicitor-binding protein (CEBiP) in the absence of PGN or chitin, and treatment with PGN or chitin led to their disassociation in vivo. OsCERK1 associated with OsLYP4 or OsLYP6 when induced by PGN but it associated with OsLYP4, OsLYP6, or CEBiP under chitin treatment, suggesting the presence of different patterns of ligand-induced heterooligomeric receptor complexes. Furthermore, the receptor-like cytoplasmic kinase OsRLCK176 functions downstream of OsCERK1 in the PGN and chitin signaling pathways, suggesting that these MAMPs share overlapping intracellular signaling components. Therefore, OsCERK1 plays dual roles in PGN and chitin signaling in rice innate immunity and as an adaptor involved in signal transduction at the plasma membrane in conjunction with OsLYP4 and OsLYP6.
01 Apr 2014
TL;DR: Chitosan was found to be effective in removing metal ions Cu(II), Zn(II, Fe(II) and Cr(IV) from industrial effluent and Antibacterial activity of the prepared chitOSan was also determined against Xanthomonas sp.
Abstract: Chitosan, a natural biopolymer composed of a linear polysaccharide of α (1–4)-linked 2-amino 2-deoxy β-d glucopyranose was synthesized by deacetylation of chitin, which is one of the major structural elements, that forms the exoskeleton of crustacean shrimps. The present study was undertaken to prepare chitosan from shrimp shell waste. The physiochemical properties like degree of deacetylation (74.82 %), ash content (2.28 %), and yield (17 %) of prepared chitosan indicated that that shrimp shell waste is a good source of chitosan. Functional property like water-binding capacity (1,136 %) and fat-binding capacity (772 %) of prepared chitosan are in total concurrence with commercially available chitosan. Fourier Transform Infra Red spectrum shows characteristic peaks of amide at 1,629.85 cm−1 and hydroxyl at 3,450.65 cm−1. X-ray diffraction pattern was employed to characterize the crystallinity of prepared chitosan and it indicated two characteristic peaks at 10° and 20° at (2θ). Scanning electron microscopy analysis was performed to determine the surface morphology. Heavy metal removal efficiency of prepared chitosan was determined using atomic absorption spectrophotometer. Chitosan was found to be effective in removing metal ions Cu(II), Zn(II), Fe(II) and Cr(IV) from industrial effluent. Antibacterial activity of the prepared chitosan was also determined against Xanthomonas sp. isolated from leaves affected with citrus canker.
TL;DR: A new class of biocompatible and biodegradable chitin-based polyurethane (PU) elastomer was introduced and reviewed in this article.
Abstract: Chitin the second most abundant polysaccharide is synthesized by an enormous number of living organisms including fungi and insects. These biopolymers have found many applications in different areas such as: packaging material, membrane for removal of metal ions, dyes and pigments in waste water engineering; anti-cholesterol, fat binding, preservative and food additive in food industry; seed and fertilizer coating, controlled agrochemical release in agriculture; surface treatment, photographic paper in pulp and paper industry; moisturizer, body creams and lotions in cosmetics and toiletries. It has also found wide applications in biomedical such as tissue engineering, drug delivery, wound dressing, scaffolds, cancer diagnosis, etc. The majority of these versatile applications are coming of its non-toxicity, biocompatibility and biodegradability. Chitin is also easily processed as gel, membrane, and nanofiber. This review emphasizes an extensive bibliography of recent basic and applied research and investigations on the aspects of this interesting biopolymer including the recovery, preparation, modification and application of chitin and its derivatives and related compounds. A new class of biocompatible and biodegradable chitin-based polyurethane (PU) elastomer was also introduced and reviewed in this study and it was found that by incorporation of chitin into the PU elastomer backbone, biocompatibility and degradation rate of the final elastomer improved. PUs are one of the synthetic biocompatible polymers with excellent physical and mechanical properties. Combination of this polymer with chitin resulted to a new tailor-made biocompatible and biodegradable polymer with improved properties. These polymers have potential applications in various applications including biomedical.
TL;DR: Chitin and chitosan were extracted from six different aquatic invertebrate species and characterized by FTIR, TGA, XRD, and SEM as mentioned in this paper, which showed that the chitins obtained from the organisms were observed in α form.
Abstract: Chitin and chitosan were extracted from six different aquatic invertebrate species. Species dry weights varied between 5 % and 20 % chitin, and the chitosan productivity of these chitins varied between 66 % and 74 %. Chitin and chitosan structures were characterized by FTIR, TGA, XRD, and SEM. FTIR results showed that the chitins obtained from the organisms were observed in α form. Chitin thermal stabilities were in the order Ranatra linearis > Anax imperator > Hydrophilus piceus > Notonecta glauca > Agabus bipustulatus > Asellus aquaticus, and chitosan thermal stabilities in the order N. glauca > A. bipustulatus > A. imperator > R. linearis > H. piceus > A. aquaticus. The crystalline index values of chitins varied between 76.4 % and 90.6 %. Their surface morphology was examined by SEM, revealing nanofibre structures. These six aquatic invertebrate species with characterized chitin and chitosan structures may be used as alternative chitin and chitosan sources for various technological purposes.
TL;DR: Overall, a platform has been developed for the surface modification of chitin fibers that provides both the physical properties ofChitin and the functional properties of Chitosan, resulting in an advanced material from a biorenewable resource with reduced chemical input.
TL;DR: The adult potato beetle is more appropriate than the larvae as an alternative chitin source because of the fact that its dry weight chitIn content, chitosan yield and purity of chit in are higher than those from the larvae, and its antimicrobial and antioxidant activities are also higher than that from the larva.
TL;DR: This study concludes that chitosan, but not chitin, stimulates IL-1β release from multiple murine and human cell types; multiple nonredundant mechanisms appear to participate in inflammasome activation by chitOSan; and chit in and ch itosan are relatively weak stimulators of inflammatory mediators from unprimed BMMΦ.
Abstract: Chitosan, the deacetylated derivative of chitin, can be found in the cell wall of some fungi and is used in translational applications. We have shown that highly purified preparations of chitosan, but not chitin, activate the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome in primed mouse bone marrow-derived macrophages (BMMΦ), inducing a robust IL-1β response. In this article, we further define specific cell types that are activated and delineate mechanisms of activation. BMMΦ differentiated to promote a classically activated (M1) phenotype released more IL-1β in response to chitosan than intermediate or alternatively activated macrophages (M2). Chitosan, but not chitin, induced a robust IL-1β response in mouse dendritic cells, peritoneal macrophages, and human PBMCs. Three mechanisms for NLRP3 inflammasome activation may contribute: K(+) efflux, reactive oxygen species, and lysosomal destabilization. The contributions of these mechanisms were tested using a K(+) efflux inhibitor, high extracellular potassium, a mitochondrial reactive oxygen species inhibitor, lysosomal acidification inhibitors, and a cathepsin B inhibitor. These studies revealed that each of these pathways participated in optimal NLRP3 inflammasome activation by chitosan. Finally, neither chitosan nor chitin stimulated significant release from unprimed BMMΦ of any of 22 cytokines and chemokines assayed. This study has the following conclusions: 1) chitosan, but not chitin, stimulates IL-1β release from multiple murine and human cell types; 2) multiple nonredundant mechanisms appear to participate in inflammasome activation by chitosan; and 3) chitin and chitosan are relatively weak stimulators of inflammatory mediators from unprimed BMMΦ. These data have implications for understanding the nature of the immune response to microbes and biomaterials that contain chitin and chitosan.
TL;DR: The synthetic method presented shows an attractive and facile route for producing low-cost chitin/lignin biosorbents with high efficiency of nickel and cadmium adsorption and will have a significant impact on the problematic issue of the utilization of chitinous waste from the seafood industry and lignin by-products from the pulp and paper industry.
Abstract: Novel, functional materials based on chitin of marine origin and lignin were prepared. The synthesized materials were subjected to physicochemical, dispersive-morphological and electrokinetic analysis. The results confirm the effectiveness of the proposed method of synthesis of functional chitin/lignin materials. Mechanism of chitin modification by lignin is based on formation of hydrogen bonds between chitin and lignin. Additionally, the chitin/lignin materials were studied from the perspective of waste water treatment. The synthetic method presented in this work shows an attractive and facile route for producing low-cost chitin/lignin biosorbents with high efficiency of nickel and cadmium adsorption (88.0% and 98.4%, respectively). The discovery of this facile method of synthesis of functional chitin/lignin materials will also have a significant impact on the problematic issue of the utilization of chitinous waste from the seafood industry, as well as lignin by-products from the pulp and paper industry.
TL;DR: A novel membrane-bound transcriptional regulator that positively regulates the small RNA (sRNA) TfoR, which posttranscriptionally enhances tfoX translation, and senses chitin oligosaccharides to activate the competence cascade, uncovering the molecular link between chit in and natural competence in this Vibrio species.
Abstract: Vibrio cholerae is naturally competent when grown on chitin. It is known that expression of the major regulator of competence, TfoX, is controlled by chitin; however, the molecular mechanisms underlying this requirement for chitin have remained unclear. In the present study, we identify and characterize a membrane-bound transcriptional regulator that positively regulates the small RNA (sRNA) TfoR, which posttranscriptionally enhances tfoX translation. We show that this regulation of the tfoR promoter is direct by performing electrophoretic mobility shift assays and by heterologous expression of this system in Escherichia coli. This transcriptional regulator was recently identified independently and was named "TfoS" (S. Yamamoto et al., Mol. Microbiol., in press, doi:10.1111/mmi.12462). Using a constitutively active form of TfoS, we demonstrate that the activity of this regulator is sufficient to promote competence in V. cholerae in the absence of chitin. Also, TfoS contains a large periplasmic domain, which we hypothesized interacts with chitin to regulate TfoS activity. In the heterologous host E. coli, we demonstrate that chitin oligosaccharides are sufficient to activate TfoS activity at the tfoR promoter. Collectively, these data characterize TfoS as a novel chitin-sensing transcriptional regulator that represents the direct link between chitin and natural competence in V. cholerae. IMPORTANCE Naturally competent bacteria can take up exogenous DNA from the environment and integrate it into their genome by homologous recombination. This ability to take up exogenous DNA is shared by diverse bacterial species and serves as a mechanism to acquire new genes to enhance the fitness of the organism. Several members of the family Vibrionaceae become naturally competent when grown on chitin; however, a molecular understanding of how chitin activates competence is lacking. Here, we identify a novel membrane-bound transcriptional regulator that is required for natural transformation in the human pathogen Vibrio cholerae. We demonstrate that this regulator senses chitin oligosaccharides to activate the competence cascade, thus, uncovering the molecular link between chitin and natural competence in this Vibrio species.
TL;DR: Biocompatible and bioresorbable composite fibers consisting of chitosan filled with anisotropic chitin nanofibrils with the length of 600-800 nm and cross section of about 11-12 nm as revealed by SEM and XRD were prepared by coagulation.
TL;DR: In this paper, the magnetic Ag-Fe3O4@chitin microspheres (MRChS) were constructed successfully by an in situ one-pot synthesis of Ag -Fe 3O4 nanoparticles onto the RChS surface.
TL;DR: With this solution based assembly, recent developments in producing biogenic chitin nanofibers using self-assembly from a solution of squid pen β-chitin in hexafluoroisopropanol are described.
TL;DR: The results revealed that the repeated freezing/thawing cycles induced the bicrosslinked networks consisted of chitin and PVA crystals in the composite gels, showing potential applications in the field of tissue engineering.
TL;DR: This review covers the recent advances of chitinases as a biocontrol agent and its various applications including preparation of medically important chitooligosaccharides, bioconversion of Chitin as well as in implementing chit inases as diagnostic and prognostic markers for numerous diseases and the prospect of their future utilization.
Abstract: Biological control of phytopathogenic fungi and insects continues to inspire the research and development of environmentally friendly bioactive alternatives. Potentially lytic enzymes, chitinases can act as a biocontrol agent against agriculturally important fungi and insects. The cell wall in fungi and protective covers, i.e. cuticle in insects shares a key structural polymer, chitin, a β-1,4-linked N-acetylglucosamine polymer. Therefore, it is advantageous to develop a common biocontrol agent against both of these groups. As chitin is absent in plants and mammals, targeting its metabolism will signify an eco-friendly strategy for the control of agriculturally important fungi and insects but is innocuous to mammals, plants, beneficial insects and other organisms. In addition, development of chitinase transgenic plant varieties probably holds the most promising method for augmenting agricultural crop protection and productivity, when properly integrated into traditional systems. Recently, human proteins with chitinase activity and chitinase-like proteins were identified and established as biomarkers for human diseases. This review covers the recent advances of chitinases as a biocontrol agent and its various applications including preparation of medically important chitooligosaccharides, bioconversion of chitin as well as in implementing chitinases as diagnostic and prognostic markers for numerous diseases and the prospect of their future utilization.