Natural Chitin Research Articles

Growing Hybrid Cuticles: Metallochitins as an Emerging Family of Bioactive Mimics of Chitin.

Inspired by the properties of natural chitin, the present work provides the first solid foundation for growing conformal ultrathin antibacterial films of organic chitin through a solvent-free molecular layer deposition (MLD) process. This work establishes the initial groundwork for growing biomimetic hybrid cuticles by combining sugar-type molecules with vapor-phase metal-organic precursors, which we term metallochitins or, more generally, metallosaccharides. The MLD process, featuring mild temperatures and solvent-free conditions, provides exceptional conformality and thickness precision, ensuring highly conformal coatings on diverse high aspect ratio substrates. In vitro testing confirmed that the MLD-grown metallochitins not only promote the growth of various cell lines but also prevent adhesion of both Gram-negative and Gram-positive bacteria. The choice of the metal in the hybrid enables selective antimicrobial activity against Gram-negative bacteria or comprehensive antibacterial effects, which can be controlled as desired.

A new strain of Rhodococcus indonesiensis T22.7.1T and its functional potential for deacetylation of chitin and chitooligsaccharides.

Chitin, abundant in marine environments, presents significant challenges in terms of transformation and utilization. A strain, T22.7.1T, with notable chitin deacetylation capabilities, was isolated from the rhizosphere of Acanthus ebracteatus in the North Sea of China. Comparative 16S rDNA sequence analysis showed that the new isolate had the highest sequence similarity (99.79%) with Rhodococcus indonesiensis CSLK01-03T, followed by R. ruber DSM 43338T, R. electrodiphilus JC435T, and R. aetherivorans 10bc312T (98.97%, 98.81%, and 98.83%, respectively). Subsequent genome sequencing and phylogenetic analysis confirmed that strain T22.7.1T belongs to the R. indonesiensis species. However, additional taxonomic characterization identified strain T22.7.1T as a novel type strain of R. indonesiensis distinct from CSLK01-03T. This study refines the taxonomic description of R. indonesiensis and investigates its application in converting chitin into chitosan. The chitin deacetylase (RiCDA) activity of strain T22.7.1T was optimized, and the enzyme was isolated and purified from the fermentation products. Through optimization, the RiCDA activity of strain T22.7.1T reached 287.02 U/mL, which is 34.88 times greater than the original enzyme's activity (8.0 U/mL). The natural CDA enzyme was purified with a purification factor of 31.83, and the specific activity of the enzyme solution reached 1200.33 U/mg. RiCDA exhibited good pH and temperature adaptability and stability, along with a wide range of substrate adaptabilities, effectively deacetylating chitin, chitooligosaccharides, N-acetylglucosamine, and other substrates. Product analysis revealed that RiCDA treatment increased the deacetylation degree (DD) of natural chitin to 83%, surpassing that of commercial chitosan. Therefore, RiCDA demonstrates significant potential as an efficient deacetylation tool for natural chitin and chitooligosaccharides, highlighting its applicability in the biorefining of natural polysaccharides.

Chitin and Its Derivative Chitosan: Distribution in Nature, Applications, and Technology Research (A Review).

The present review highlights the chitin/chitosan as biopolymers that are promising for biomedical research development. Our goal was to assess the potential for practical use of these biopolymers and to summarize information on traditional and innovative technologies for their production and purification. The widespread occurrence of chitin and chitosan in nature as well as the unique chemical and biological properties of chitosan are reasons of growing interest in the use of the latter in several pharmaceutical fields. The main stages of chitin extraction and its further modification into chitosan are deproteinization, demineralization, deacetylation, and the main methods of chitosan purification are filtration, dialysis and reprecipitation. The profitability of the production of chitin/chitosan from crustaceans and edible mushrooms is approximately at the same level. The cost of mushroom products can be reduced by using agricultural or forestry waste as nutrient substrates. This makes the use of fungi as sources of chitin/chitosan in forested regions a rather promising issue.

Insights into peculiar fungal LPMO family members holding a short C-terminal sequence reminiscent of phosphate binding motifs

Lytic polysaccharide monooxygenases (LPMOs) are taxonomically widespread copper-enzymes boosting biopolymers conversion (e.g. cellulose, chitin) in Nature. White-rot Polyporales, which are major fungal wood decayers, may possess up to 60 LPMO-encoding genes belonging to the auxiliary activities family 9 (AA9). Yet, the functional relevance of such multiplicity remains to be uncovered. Previous comparative transcriptomic studies of six Polyporales fungi grown on cellulosic substrates had shown the overexpression of numerous AA9-encoding genes, including some holding a C-terminal domain of unknown function (“X282”). Here, after carrying out structural predictions and phylogenetic analyses, we selected and characterized six AA9-X282s with different C-term modularities and atypical features hitherto unreported. Unexpectedly, after screening a large array of conditions, these AA9-X282s showed only weak binding properties to cellulose, and low to no cellulolytic oxidative activity. Strikingly, proteomic analysis revealed the presence of multiple phosphorylated residues at the surface of these AA9-X282s, including a conserved residue next to the copper site. Further analyses focusing on a 9 residues glycine-rich C-term extension suggested that it could hold phosphate-binding properties. Our results question the involvement of these AA9 proteins in the degradation of plant cell wall and open new avenues as to the divergence of function of some AA9 members.

Solid-liquid equilibrium of glucosamine hydrochloride in four binary solvents: Experiments, modeling, and molecular simulation

Glucosamine hydrochloride (GAH) is a marine biological preparation derived from natural chitin and improves articular cartilage metabolism. In this study, the solubility of GAH in four binary solvents (water + methanol, water + ethanol, water + isopropanol, and water + acetone) was gravimetrically determined over the temperature range of 283.15 K to 323.15 K. The solubility of GAH were found increasing monotonically with water content and temperature. In alcohol mixtures, the solubility of GAH can be ranked as: (water + methanol) > (water + ethanol) > (water + isopropanol). Four thermodynamic models (the modified Apelblat equation, van't Hoff equation, (CNIBS)/R-K model and Jouyban-Acree model) were used to correlate the experimental solubility data, which the (CNIBS)/R-K model showed the best fitting performance. The dissolution thermodynamic properties of GAH were also calculated. The results indicate that the dissolution process is driven by both entropy and enthalpy. To explore the solid–liquid equilibrium behavior from molecular level, the Hirshfeld surface of GAH crystal was generated and molecular dynamics simulations of mixed systems were performed. Based on equilibrium configurations of different mixtures, molecular interactions between solvent–solvent and solute–solvent were calculated. Meanwhile, the simulation snapshots and radial distribution function plots were analyzed to interpret association of solvents.

A Review of Chitosan and Chitosan Nanofiber: Preparation, Characterization, and Its Potential Applications

Chitosan is produced by deacetylating the abundant natural chitin polymer. It has been employed in a variety of applications due to its unique solubility as well as its chemical and biological properties. In addition to being biodegradable and biocompatible, it also possesses a lot of reactive amino side groups that allow for chemical modification and the creation of a wide range of useful derivatives. The physical and chemical characteristics of chitosan, as well as how it is used in the food, environmental, and medical industries, have all been covered in a number of academic publications. Chitosan offers a wide range of possibilities in environmentally friendly textile processes because of its superior absorption and biological characteristics. Chitosan has the ability to give textile fibers and fabrics antibacterial, antiviral, anti-odor, and other biological functions. One of the most well-known and frequently used methods to create nanofibers is electrospinning. This technique is adaptable and effective for creating continuous nanofibers. In the field of biomaterials, new materials include nanofibers made of chitosan. Numerous medications, including antibiotics, chemotherapeutic agents, proteins, and analgesics for inflammatory pain, have been successfully loaded onto electro-spun nanofibers, according to recent investigations. Chitosan nanofibers have several exceptional qualities that make them ideal for use in important pharmaceutical applications, such as tissue engineering, drug delivery systems, wound dressing, and enzyme immobilization. The preparation of chitosan nanofibers, followed by a discussion of the biocompatibility and degradation of chitosan nanofibers, followed by a description of how to load the drug into the nanofibers, are the first issues highlighted by this review of chitosan nanofibers in drug delivery applications. The main uses of chitosan nanofibers in drug delivery systems will be discussed last.

Liquefied chitin-derived super tough, sustainable, and anti-bacterial polyurethane elastomers

Considerable amounts of waste chitin are produced every year from the fishing industry; however, the efficient utilization of natural chitin remains a challenge. To expand the applications of natural chitin, we herein report the thermal liquefaction of chitin to promote chain extension and synthesize a liquefied chitin-based polyurethane (LCPU) elastomer with a desirable tensile strength (∼43 MPa), superior toughness (∼417.66 MJ m−3), and an extremely high fracture energy (∼567.89 kJ m−2). In this study, liquefied chitin was used for the first time as a chain extender to replace traditional polyols and polyamino compounds in the preparation of tough PU materials. The acquired extraordinary mechanical features mainly originated from the highly efficient energy dissipation of strong hydrogen-bonding clusters and strain-induced crystal structures. The prepared LCPU materials exhibited considerable recyclability and self-healing properties owing to their dynamic hydrogen bonding. In addition, they exhibited excellent anti-bacterial properties and a good biocompatibility, thereby indicating their potential for application in biomedicine, such as in the contexts of minimally invasive surgical procedures and anti-bacterial medical instruments. We believe that this strategy will encourage researchers in academia and industry to develop strong, tough, degradable, and biosafe elastic materials from natural resources.

Isolation and screening of a chitin deacetylase producing Bacillus cereus and its potential for chitosan preparation.

Chitosan is a biopolymer material extracted from marine biomass waste such as shrimp and crab shells, which has good biocompatibility and degradability with great potential for application in the field of wastewater treatment and soil remediation. The higher the degree of deacetylation (DD), the better the adsorption performance of chitosan. Chitin deacetylase (CDA) can specifically catalyze the deacetylate of chitin in a green reaction that is environmentally friendly. However, the scarcity of high yielding chitin deacetylase strains has been regarded as the technical bottleneck of chitosan green production. Here, we screened a natural chitin degrading bacterium from coastal mud and identified it as Bacillus cereus ZWT-08 by re-screening the chitin deacetylase activity and degree of deacetylation values. By optimizing the medium conditions and enzyme production process, ZWT-08 was cultured in fermentation medium with 1% (m/V) glucose and yeast extract at pH 6.0, 37°C, and a stirring speed of 180 r/min. After fermenting in 5L fermenter for 48 h, the deacetylation activity of the supernatant reached 613.25 U/mL. Electron microscopic examination of the chitin substrate in the fermentation medium revealed a marshmallow-like fluffy texture on its structural surface. Meanwhile, 89.29% of the acetyl groups in this chitin substrate were removed by enzymatic digestion of chitin deacetylase produced by ZWT-08, resulting in the preparation of chitosan a degree of deacetylation higher than 90%. As an effective strain for chitosan production, Bacillus cereus ZWT-08 plays a positive role in the bioconversion of chitin and the upgrading of the chitosan industry.

Characterization of chitinases from the GH18 gene family in the myxomycete Physarum polycephalum

BackgroundPhysarum polycephalum is an unusual macroscopic myxomycete expressing a large range of glycosyl hydrolases. Among them, enzymes from the GH18 family can hydrolyze chitin, an important structural component of the cell walls in fungi and in the exoskeleton of insects and crustaceans. MethodsLow stringency sequence signature search in transcriptomes was used to identify GH18 sequences related to chitinases. Identified sequences were expressed in E. coli and corresponding structures modelled. Synthetic substrates and in some cases colloidal chitin were used to characterize activities. ResultsCatalytically functional hits were sorted and their predicted structures compared. All share the TIM barrel structure of the GH18 chitinase catalytic domain, optionally fused to binding motifs, such as CBM50, CBM18, and CBM14, involved in sugar recognition. Assessment of the enzymatic activities following deletion of the C-terminal CBM14 domain of the most active clone evidenced a significant contribution of this extension to the chitinase activity. A classification based on module organization, functional and structural criteria of characterized enzymes was proposed. ConclusionsPhysarum polycephalum sequences encompassing a chitinase like GH18 signature share a modular structure involving a structurally conserved catalytic TIM barrels decorated or not by a chitin insertion domain and optionally surrounded by additional sugar binding domains. One of them plays a clear role in enhancing activities toward natural chitin. General significanceMyxomycete enzymes are currently poorly characterized and constitute a potential source for new catalysts. Among them glycosyl hydrolases have a strong potential for valorization of industrial waste as well as in therapeutic field.

Chitosan: A biopolymer for textile processes and products

Chitosan is a biopolymer obtained from deacetylation of the abundant natural chitin polymer. It has found its use in many applications due to its unique solubility as well as chemical and biological properties. In addition to its biodegradability and biocompatibility, it has many reactive amino side groups that offer the possibilities of chemical modification and formation of a large variety of beneficial derivatives. Numerous researchers have published works outlining the physical and chemical properties of chitosan, as well as its use in several industries, such as medical, environmental and food. Due to its excellent absorption and biological properties, chitosan present a myriad of opportunities in eco-friendly textile processes. Chitosan is able to confer antimicrobial, antiviral, anti-odor and other biological activities to textile fibers and fabrics. In this review, the first part is dedicated to developing the physio-chemical and biological characteristics of chitosan. Then, we present chitosan applications in the textile industry over the past decade. Literature works on chitosan usage along with different textile production steps (fiber formation, functional treatments, dyeing and effluent treatment) are extensively discussed.

Economical Chemical Recycling of Complex PET Waste in the Form of Active Packaging Material

Since millions of tons of packaging material cannot be recycled in conventional ways, most of it ends up in landfills or even dumped into the natural environment. The researched methods of chemical depolymerization therefore open a new perspective for the recycling of various PET materials, which are especially important for packaging. Food preservative packaging materials made from PET plastics are complex, and their wastes are often contaminated, so there are no sophisticated solutions for them in the recycling industry. After integrating the biopolymer chitosan, which is derived from natural chitin, as an active surface additive in PET materials, we discovered that it not only enriches the packaging material as a microbial inhibitor to reduce the bacteria Staphylococcus aureus and Escherichia coli, thus extending the shelf life of the contained food, but also enables economical chemical recycling by alkaline or neutral hydrolysis, which is an environmentally friendly process. Alkaline hydrolysis at a high temperature and pressure completely depolymerizes chitosan-coated PET packaging materials into pure terephthalic acid and charcoal. The products were characterized by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and elemental analysis. The resulting reusable material represents raw materials in chemical, plastic, textile, and other industries, in addition to the antimicrobial function and recyclability itself.

Chitinase enzyme in bacterial species and fungal growth inhibition against A. niger and Penicillium

Chitin is the most abundant polysaccharide in nature, second after cellulose as it found in the structure of crustaceans, insects and fungi being a significant component. Sea food waste disposal pose a great problem as chitin in nature degrade at a very gradual rate. Efforts are being made to use chitinase enzyme from different organisms to increase the rate and efficiency of chitin waste disposal. Moreover, chitinase and chitinase producing bacteria are widely being exploited to be used as bio-control agents to inhibit crop pathogens. On the basis of its mechanism of action, chitinase can either be endochitnase or exochitinase. Endo chitinases randomly hydrolyses internal glycosidic bonds in chitin. Exochitinase is exoglycosidase that can be divided into two subtypes based on the specificity of their action Chitinase is synthesized by a number of different microbes including bacteria, fungi and other organisms like mammals, insects etc. This paper gives information about the production of different chitinase enzymes from different bacterial gram-positive species. Antifungal activity for different isolates were tested against A. niger and Penicillium. The isolates showed varying degree of fungal growth inhibition against different fungi.

High yield production of chitin nanocrystals via hydrochloric acid vapor pre-treatment

Traditionally, chitin nanocrystals (ChNCs) are extracted from natural chitin suffered from huge chemical consumption and low yields. Herein, we show that ChNCs can be prepared in yields up to 95.5% by a pretreatment process using HCl vapor to assist exfoliation. It is shown that HCl vapor mainly caused disintegration of amorphous chitin, without excessive hydrolysis of the crystalline region. TEM images showed that chitin exposed to HCl vapor for a certain time readily separated into discernable rods with diameters in the nanoscale range. XRD and TGA analysis showed that the crystallinity and thermal stability of ChNCs were comparable to those of the untreated chitin. In addition, ChNCs was applied as efficient stabilizer for oil-in-water (O/W) emulsions.

Improving Polysaccharide-Based Chitin/Chitosan-Aerogel Materials by Learning from Genetics and Molecular Biology.

Improved wound healing of burnt skin and skin lesions, as well as medical implants and replacement products, requires the support of synthetical matrices. Yet, producing synthetic biocompatible matrices that exhibit specialized flexibility, stability, and biodegradability is challenging. Synthetic chitin/chitosan matrices may provide the desired advantages for producing specialized grafts but must be modified to improve their properties. Synthetic chitin/chitosan hydrogel and aerogel techniques provide the advantages for improvement with a bioinspired view adapted from the natural molecular toolbox. To this end, animal genetics provide deep knowledge into which molecular key factors decisively influence the properties of natural chitin matrices. The genetically identified proteins and enzymes control chitin matrix assembly, architecture, and degradation. Combining synthetic chitin matrices with critical biological factors may point to the future direction with engineering materials of specific properties for biomedical applications such as burned skin or skin blistering and extensive lesions due to genetic diseases.

A Review of Various Sources of Chitin and Chitosan in Nature

Chitin was first discovered by its name from the Greek word “chiton”, which means “mail coat”. It is indeed a polysaccharide made up of naturally occurring acetyl-D-glucosamine monomers. Hatchett was the first researcher who extracted chitin from the shells of mollusks (crabs and lobsters), prawns, and crayfish in 1799. Later in 1811, Henri Braconnot discovered chitin in the cell walls of mushrooms and called it “fungine”. Chitin and chitosan are abundant in the biosphere as essential components of many organisms’ exoskeletons and as by-products of the global seafood industry. The biopolymer must be deacetylated before chitosan can be produced. It can also be extracted using microbes in a biological extraction procedure. The development of products that take advantage of the bioactivities of the existing primary commercial source of chitin (crustacean) has lagged expectations. Also, the disadvantages of the present commercial source such as seasonality and competition for other uses among others has been one of the driving forces towards seeking alternative sources of chitin and chitosan in nature. This review highlights some of the efforts made by environmental scholars to locate possible commercial sources of chitin and chitosan in nature over time.

Public good exploitation in natural bacterioplankton communities.

Bacteria often interact with their environment through extracellular molecules that increase access to limiting resources. These secretions can act as public goods, creating incentives for exploiters to invade and "steal" public goods away from producers. This phenomenon has been studied extensively in vitro, but little is known about the occurrence and impact of public good exploiters in the environment. Here, we develop a genomic approach to systematically identify bacteria that can exploit public goods produced during the degradation of polysaccharides. Focusing on chitin, a highly abundant marine biopolymer, we show that public good exploiters are active in natural chitin degrading microbial communities, invading early during colonization, and potentially hindering degradation. In contrast to in vitro studies, we find that exploiters and degraders belong to distant lineages, facilitating their coexistence. Our approach opens novel avenues to use the wealth of genomic data available to infer ecological roles and interactions among microbes.

Iron Based Chitin Composite Films for Efficient Solar Seawater Desalination

Seawater desalination provides a convenient method for the sustainable production of fresh water. However, the preparation of low-cost, high-efficiency solar absorbers remains a huge challenge. To this end, our research group designed and produced a cheap absorber—a membrane made of natural polymer chitin with black FeS and Fe3O4, respectively. Due to the hierarchical pore structure, excellent photothermal performance and good hydrophilicity of the film, their water evaporation rates reached 1.47 kg/m2/h and 1.55 kg/m2/h under one sunlight, respectively. Under about 10 suns, the highest desalination efficiency of FeS/chitin and Fe3O4/chitin are 90% and 74%, respectively, and their salinities are also in line with the World Health Organization drinking water standards. These results indicate the potential of chitin-based nanomaterials as high-efficiency solar absorbers to produce fresh water.

Chitosan as capping agent in a robust one-pot procedure for a magnetic catalyst synthesis

Here, we report a one-pot solvothermal method for the development of magnetically recoverable catalysts with Ru or Ag nanoparticles (NPs) capped by chitosan (CS), a derivative of natural chitin. The formation of iron oxide NPs was carried out in situ in the presence of CS and iron acetylacetonate in boiling triethyleneglycol (TEG) due to CS solubilization in warm TEG. Coordination with Ru or Ag species and the NP formation take place in the same reaction solution, eliminating intermediate steps. In optimal conditions the method developed allows stabilization of 2.2 nm monodisperse Ru NPs (containing both Ru0 and Ru4+ species) that are evenly distributed through the catalyst, while for Ag NPs, this stabilizing medium is inferior, leading to exceptionally large Ag nanocrystals. Catalytic testing of CS-Ru magnetically recoverable catalysts in the reduction of 4-nitrophenol to 4-aminophenol with excess NaBH4 revealed that the catalyst with 2.2 nm Ru NPs exhibits the highest catalytic activity compared to samples with larger Ru NPs (2.9–3.2 nm). Moreover, this catalyst displayed extraordinary shelf-life in the aqueous solution (up to ten months) and excellent reusability in ten consecutive reactions with easy magnetic separation at each step which were assigned to its conformational rigidity at a constant pH. These characteristics as well as favorable environmental factors of the catalyst fabrication, make it promising for nitroarene reduction.

The synergistic effect of Co/CoO hybrid structure combined with biomass materials promotes photocatalytic hydrogen evolution

Developing photocatalysts with high efficiency and low cost for water splitting is significant in the production of hydrogen using solar energy. In this report, a low-cost and environmentally-friendly photocatalyst (Co-CN-500) is achieved through a simple calcination procedure with natural chitin and cobalt nitrate as raw materials. With Eosin Y as photosensitizer in triethanolamine (TEOA) solution, the hydrogen evolution rate of Co-CN-500 can reach 12.63 mmol g-1 h-1, which is higher than that of commercial Pt-C (10.34 mmol g-1 h-1) and other reported cobalt-containing photocatalysts. Characterization results prove the hybrid structure of cobalt ingredients involving cobalt monoxide and metal cobalt is essential for excellent photocatalytic performance. DFT calculations confirm the free energy of hydrogen adsorption and work function on Co/CoO hybrid surface are smaller than on Co (111) and CoO (111), making it easier to form adsorbed H that then produce H2.

Sustainable carbon-based nanostructures with optoelectronic performance inspired by crustacean shells towards biomimetic pyrolysis and hydrothermal liquid crystal transfer

In this work, we exploit new sustainable carbon-based nanostructures by investigating the biomimetic pyrolysis and hydrothermal liquid crystal transfer of natural chitin nanofibrils. Chitin nanofibrils with Bouligand structure in the original crab shell are thermally carbonized to yield helical mesoporous carbon replicas. Monodisperse oleic acid-capped cobalt oxide nanoparticles are impregnated into helical pores in the carbonized membranes to generate hierarchical mesoporous Co3O4/C nanocomposites that are functionable as a freestanding, binder free supercapacitor. Towards colloidal chemistry of photoluminescent chitin-derived carbon nanoparticles, chitin nanorods prepared by acid hydrolysis of crab shell-extracted chitin disperse in water to form chitin liquid crystals that are used as a new carbon precursor for the carbonized transformation. Hydrophobic oleic acid-stabilized carbon nanorod colloids with optical response are primarily synthesized by hydrothermal phase transfer carbonization of chitin liquid crystals. The structural integrity of chitin nanorods can be preserved during liquid-liquid phase transformation to form carbon nanorods. The carbon anisotropic nanocolloids hydrophobically dispersed in toluene exhibit green photoluminescent emission in the visible region, which optically respond to trinitrotoluene. Our chitin inspiration paves a way to pursue further investigation of the electrochemical catalysis for the mesoporous Co3O4/C nanohelices and the sensing and optical coating for the photoluminescent carbon nanorod colloids.