Showing papers on "Chitin published in 2015"

Chitin and Chitosan Preparation from Marine Sources. Structure, Properties and Applications

Abstract: This review describes the most common methods for recovery of chitin from marine organisms. In depth, both enzymatic and chemical treatments for the step of deproteinization are compared, as well as different conditions for demineralization. The conditions of chitosan preparation are also discussed, since they significantly impact the synthesis of chitosan with varying degree of acetylation (DA) and molecular weight (MW). In addition, the main characterization techniques applied for chitin and chitosan are recalled, pointing out the role of their solubility in relation with the chemical structure (mainly the acetyl group distribution along the backbone). Biological activities are also presented, such as: antibacterial, antifungal, antitumor and antioxidant. Interestingly, the relationship between chemical structure and biological activity is demonstrated for chitosan molecules with different DA and MW and homogeneous distribution of acetyl groups for the first time. In the end, several selected pharmaceutical and biomedical applications are presented, in which chitin and chitosan are recognized as new biomaterials taking advantage of their biocompatibility and biodegradability.

A Review on Chitin and Chitosan Polymers: Structure, Chemistry, Solubility, Derivatives, and Applications

Abstract: Chitin and chitosan are considerably versatile and promising biomaterials. The deacetylated chitin derivative chitosan is a useful and interesting bioactive polymer. Despite its biodegradability, it has many reactive amino side groups, which offer possibilities of chemical modifications, formation of a large variety of beneficial derivatives, which are commercially available or can be made available via graft reactions and ionic interactions. This study looks at the contemporary research in chitin and chitosan towards structure, properties, and applications in various industrial and biomedical fields.

Chitin, Chitosan, and Its Derivatives for Wound Healing: Old and New Materials

Abstract: Chitin (β-(1-4)-poly-N-acetyl-D-glucosamine) is widely distributed in nature and is the second most abundant polysaccharide after cellulose. It is often converted to its more deacetylated derivative, chitosan. Previously, many reports have indicated the accelerating effects of chitin, chitosan, and its derivatives on wound healing. More recently, chemically modified or nano-fibrous chitin and chitosan have been developed, and their effects on wound healing have been evaluated. In this review, the studies on the wound-healing effects of chitin, chitosan, and its derivatives are summarized. Moreover, the development of adhesive-based chitin and chitosan are also described. The evidence indicates that chitin, chitosan, and its derivatives are beneficial for the wound healing process. More recently, it is also indicate that some nano-based materials from chitin and chitosan are beneficial than chitin and chitosan for wound healing. Clinical applications of nano-based chitin and chitosan are also expected.

The battle for chitin recognition in plant-microbe interactions

Abstract: Fungal cell walls play dynamic functions in interaction of fungi with their surroundings. In pathogenic fungi, the cell wall is the first structure to make physical contact with host cells. An important structural component of fungal cell walls is chitin, a well-known elicitor of immune responses in plants. Research into chitin perception has sparked since the chitin receptor from rice was cloned nearly a decade ago. Considering the widespread nature of chitin perception in plants, pathogens evidently evolved strategies to overcome detection, including alterations in the composition of cell walls, modification of their carbohydrate chains and secretion of effectors to provide cell wall protection or target host immune responses. Also non-pathogenic fungi contain chitin in their cell walls and are recipients of immune responses. Intriguingly, various mutualists employ chitin-derived signaling molecules to prepare their hosts for the mutualistic relationship. Research on the various types of interactions has revealed different molecular components that play crucial roles and, moreover, that various chitin-binding proteins contain dissimilar chitin-binding domains across species that differ in affinity and specificity. Considering the various strategies from microbes and hosts focused on chitin recognition, it is evident that this carbohydrate plays a central role in plant–fungus interactions.

Discovery of the combined oxidative cleavage of plant xylan and cellulose by a new fungal polysaccharide monooxygenase

Abstract: Many agricultural and industrial food by-products are rich in cellulose and xylan. Their enzymatic degradation into monosaccharides is seen as a basis for the production of biofuels and bio-based chemicals. Lytic polysaccharide monooxygenases (LPMOs) constitute a group of recently discovered enzymes, classified as the auxiliary activity subgroups AA9, AA10, AA11 and AA13 in the CAZy database. LPMOs cleave cellulose, chitin, starch and β-(1 → 4)-linked substituted and non-substituted glucosyl units of hemicellulose under formation of oxidized gluco-oligosaccharides. Here, we demonstrate a new LPMO, obtained from Myceliophthora thermophila C1 (MtLPMO9A). This enzyme cleaves β-(1 → 4)-xylosyl bonds in xylan under formation of oxidized xylo-oligosaccharides, while it simultaneously cleaves β-(1 → 4)-glucosyl bonds in cellulose under formation of oxidized gluco-oligosaccharides. In particular, MtLPMO9A benefits from the strong interaction between low substituted linear xylan and cellulose. MtLPMO9A shows a strong synergistic effect with endoglucanase I (EGI) with a 16-fold higher release of detected oligosaccharides, compared to the oligosaccharides release of MtLPMO9A and EGI alone. Now, for the first time, we demonstrate the activity of a lytic polysaccharide monooxygenase (MtLPMO9A) that shows oxidative cleavage of xylan in addition to cellulose. The ability of MtLPMO9A to cleave these rigid regions provides a new paradigm in the understanding of the degradation of xylan-coated cellulose. In addition, MtLPMO9A acts in strong synergism with endoglucanase I. The mode of action of MtLPMO9A is considered to be important for loosening the rigid xylan–cellulose polysaccharide matrix in plant biomass, enabling increased accessibility to the matrix for hydrolytic enzymes. This discovery provides new insights into how to boost plant biomass degradation by enzyme cocktails for biorefinery applications.

Highly Biocompatible Nanofibrous Microspheres Self‐Assembled from Chitin in NaOH/Urea Aqueous Solution as Cell Carriers

Abstract: In this work, chitin microspheres (NCM) having a nanofibrous architecture were constructed using a “bottom-up” fabrication pathway. The chitin chains rapidly self-assembled into nanofibers in NaOH/urea aqueous solution by a thermally induced method and subsequently formed weaved microspheres. The diameter of the chitin nanofibers and the size of the NCM were tunable by controlling the temperature and the processing parameters to be in the range from 26 to 55 nm and 3 to 130 μm, respectively. As a result of the nanofibrous surface and the inherent biocompatibility of chitin, cells could adhere to the chitin microspheres and showed a high attachment efficiency, indicating the great potential of the NCM for 3D cell microcarriers.

Extraction and characterization of chitin and chitosan from fishery waste by chemical method

Abstract: After cellulose, chitin is the most widespread biopolymer available in nature. Chitin has economic value because of its biological activities, industrial and biomedical applications. There are three sources of chitin, namely crustaceans, insects and microorganism. The commercial sources of chitin are shells of crustaceans such as shrimp, crabs, lobsters and krill. In the present study, chitin has been extracted from locally available fish in Rourkela. The obtained chitin was converted into the more useful chitosan. The obtained chitin and chitosan have been characterized by using different techniques like spectral analysis, X-ray diffraction, Elemental analysis, Fourier transforms infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Differential scanning calorimetry (DSC). XRD analysis indicated the crystalline nature of the chitin and chitosan. The FTIR patterns displayed the bands corresponding to stretching and vibration of O-H, N-H and CO bonds and conformed the formation of α -chitin. Degree of deacetylation (DD) value was calculated using elemental analysis, potentiometric titration and FTIR. Using FTIR analysis DD value was found to be 61%.

Chitinases from Bacteria to Human: Properties, Applications, and Future Perspectives

Abstract: Chitin is the second most plenteous polysaccharide in nature after cellulose, present in cell walls of several fungi, exoskeletons of insects, and crustacean shells. Chitin does not accumulate in the environment due to presence of bacterial chitinases, despite its abundance. These enzymes are able to degrade chitin present in the cell walls of fungi as well as the exoskeletons of insect. They have shown being the potential agents for biological control of the plant diseases caused by various pathogenic fungi and insect pests and thus can be used as an alternative to chemical pesticides. There has been steady increase in demand of chitin derivatives, obtained by action of chitinases on chitin polymer for various industrial, clinical, and pharmaceutical purposes. Hence, this review focuses on properties and applications of chitinases starting from bacteria, followed by fungi, insects, plants, and vertebrates. Designing of chitinase by applying directed laboratory evolution and rational approaches for improved catalytic activity for cost-effective field applications has also been explored.

Genomic Potential for Polysaccharide Deconstruction in Bacteria

Abstract: Glycoside hydrolases are important enzymes that support bacterial growth by enabling the degradation of polysaccharides (e.g., starch, cellulose, xylan, and chitin) in the environment. Presently, little is known about the overall phylogenetic distribution of the genomic potential to degrade these polysaccharides in bacteria. However, knowing the phylogenetic breadth of these traits may help us predict the overall polysaccharide processing in environmental microbial communities. In order to address this, we identified and analyzed the distribution of 392,166 enzyme genes derived from 53 glycoside hydrolase families in 8,133 sequenced bacterial genomes. Enzymes for oligosaccharides and starch/glycogen were observed in most taxonomic groups, whereas glycoside hydrolases for structural polymers (i.e., cellulose, xylan, and chitin) were observed in clusters of relatives at taxonomic levels ranging from species to genus as determined by consenTRAIT. The potential for starch and glycogen processing, as well as oligosaccharide processing, was observed in 85% of the strains, whereas 65% possessed enzymes to degrade some structural polysaccharides (i.e., cellulose, xylan, or chitin). Potential degraders targeting one, two, and three structural polysaccharides accounted for 22.6, 32.9, and 9.3% of genomes analyzed, respectively. Finally, potential degraders targeting multiple structural polysaccharides displayed increased potential for oligosaccharide deconstruction. This study provides a framework for linking the potential for polymer deconstruction with phylogeny in complex microbial assemblages.

Extraction and Characterization of Chitin and Chitosan with Antimicrobial and Antioxidant Activities from Cosmopolitan Orthoptera Species (Insecta)

Abstract: This study examined two gregarious Orthoptera species (Calliptamus barbarus and Oedaleus decorus) as potential sources of chitin. The chitin content of the dry weight of C. barbarus was 20.5 ± 0.7%, and it was 16.5 ± 0.7% for O. decorus. Furthermore, the yield of chitosan (70 ~ 75% deacetylation degree) from the grasshopper species was found to be 74 ~ 76%, which is close to the yield of commercial preparations obtained from the unused parts of crabs and shrimp. The chitin and chitosan obtained in this way were analyzed using FTIR, TGA, XRD and SEM techniques, and the antimicrobial properties of chitosans obtained from C. barbarus and O. decorus against pathogenic microorganisms of humans and fish were investigated using the disc diffusion and microdilution broth methods. The antimicrobial screening procedures indicated that the chitosan showed significant antimicrobial activity against all of the tested pathogenic microorganisms. The MBC or MFC values were determined to be 0.16 ~ 2.50 mg/mL. The IC50 values for the chitins obtained from C. barbarus and O. decorus were 10.68 ± 0.27 and 10.91 ± 0.96 mg/mL, respectively, which were greater than the value for butylated hydroxytoluene (BHT): 0.04 ± 0.01 mg/mL. These results suggest that these two species, which are currently considered to be pests because of over-breeding, are potentially alternative sources of chitin and chitosan, which are used in the food/feed industry for their antimicrobial and antioxidant properties.

Enzymatic production of defined chitosan oligomers with a specific pattern of acetylation using a combination of chitin oligosaccharide deacetylases

Abstract: Chitin and chitosan oligomers have diverse biological activities with potentially valuable applications in fields like medicine, cosmetics, or agriculture. These properties may depend not only on the degrees of polymerization and acetylation, but also on a specific pattern of acetylation (PA) that cannot be controlled when the oligomers are produced by chemical hydrolysis. To determine the influence of the PA on the biological activities, defined chitosan oligomers in sufficient amounts are needed. Chitosan oligomers with specific PA can be produced by enzymatic deacetylation of chitin oligomers, but the diversity is limited by the low number of chitin deacetylases available. We have produced specific chitosan oligomers which are deacetylated at the first two units starting from the non-reducing end by the combined use of two different chitin deacetylases, namely NodB from Rhizobium sp. GRH2 that deacetylates the first unit and COD from Vibrio cholerae that deacetylates the second unit starting from the non-reducing end. Both chitin deacetylases accept the product of each other resulting in production of chitosan oligomers with a novel and defined PA. When extended to further chitin deacetylases, this approach has the potential to yield a large range of novel chitosan oligomers with a fully defined architecture.

Effect of Treatment Methods on Chitin Structure and Its Transformation into Nitrogen-Containing Chemicals

Abstract: Chitin treatment using different methods, including ball mill grinding, steam explosion, alkaline treatment, phosphoric acid, and ionic liquid (IL) dissolution/reprecipitation have been systematically investigated. The chitin structures were thoroughly investigated by using a series of analytical techniques, and the reactivity after each treatment was evaluated in dehydration and liquefaction reactions. The parallel studies enable direct comparisons of these methods and help to establish the structure-activity correlations. Ball mill grinding in dry mode was the most effective method, with the crystal size and the hydrogen-bond network being the two crucial factors in enhancing the reactivity. Remarkably, the yield of 3-acetamido-5-acetylfuran (3A5AF) from chitin dehydration increased to the highest amount (28.5 %) after ball mill grinding (the previous record yield was 7.5% for untreated chitin).

Conversion of chitin and N-acetyl-D-glucosamine into a N-containing furan derivative in ionic liquids

Abstract: Direct conversion of chitin to 3-acetamido-5-acetylfuran (3A5AF) in a range of ionic liquids (ILs) has been systematically investigated. 10 ILs with different cations and anions were tested as the solvent and 25 additives were screened. The results revealed that the presence of Cl in the IL is essential. In addition to the solubility enhancement of chitin in Cl containing ILs, the Cl anion appeared to participate in the chitin reaction cycle in IL solvents. 3A5AF can be obtained in some ILs, such as [BMIm]Cl, without any additive. Significantly enhanced yields of 3A5AF were obtained in [BMIm]Cl using boric acid and hydrochloric acid (HCl) as additives at 180 °C, a lower temperature than using organic solvents (215 °C). Kinetic studies showed that the product formed very quickly within 10 min, with much higher initial rate than using organic solvents. Recovered chitin was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and elemental analysis (EA). In an effort to improve the yield, extraction and distillation were attempted for both chitin and chitin monomer, N-acetyl-D-glucosamine (NAG). Further studies were performed on NAG to see if acidic ILs would lead to enhanced reactivity. However, these were less effective.

Differentiations of Chitin Content and Surface Morphologies of Chitins Extracted from Male and Female Grasshopper Species

Abstract: In this study, we used Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), thermogravimetric analysis (TGA), X-ray diffractometry (XRD), and scanning electron microscopy (SEM) to investigate chitin structure isolated from both sexes of four grasshopper species. FT-IR, EA, XRD, and TGA showed that the chitin was in the alpha form. With respect to gender, two main differences were observed. First, we observed that the quantity of chitin was greater in males than in females and the dry weight of chitin between species ranged from 4.71% to 11.84%. Second, using SEM, we observed that the male chitin surface structure contained 25-90 nm wide nanofibers and 90-250 nm nanopores, while no pores or nanofibers were observed in the chitin surface structure of the majority of females (nanofibers were observed only in M. desertus females). In contrast, the elemental analysis, thermal properties, and crystalline index values for chitin were similar in males and females. Also, we carried out enzymatic digestion of the isolated chitins using commercial chitinase from Streptomyces griseus. We observed that there were no big differences in digestion rate of the chitins from both sexes and commercial chitin. The digestion rates were for grasshoppers' chitins; 88.45-95.48% and for commercial chitin; 94.95%.

Environmental applications of chitosan and its derivatives.

Abstract: Seafood processing waste is a potentially rich source of several useful products including chitin (Meanwell and Shama 2008), and has long been generated in large tonnages worldwide (Chang et al. 2007). Chitin is economical and is the second most abundant bio-waste material after cellulose (Shahidi et al. 1999). Annual worldwide chitin production from arthropods (e.g., crustaceans and insects), molluscs (e.g., squid and cuttlefish) and fungi is estimated at about 100 × 109 t (Tharanathan and Kittur 2003). A steady supply of chitinous waste materials from the seafood processing industry has been the major source of commercial products such as chitin and chitosan (Hayes 2012). The increasing consumption of krill oil and mushrooms has also been an additional source for commercial chitin (Nicol and Hosie 1993; Vetter 2007).