Showing papers on "Chitin published in 2021"
TL;DR: The history as well as the current progress in the analytical methods for chitin identification are outlined and biochemical and immunochemical methods are described with respect to their medical application.
89 citations
TL;DR: The present review summarizes the current chemical methods for chitin recovery and production of its most common derivative, the deacetylated form named chitosan, from shrimp shell wastes.
71 citations
TL;DR: The wastes of edible insect breeding should be collected and evaluated as an alternative of chitin/chitosan source and characterized using DSC, FT-IR, XRD, TGA, and SEM techniques demonstrate consistency with the degree of deacetylation of the obtained chitOSan, allowing the differentiation between chit in and chitosans.
60 citations
TL;DR: Chitin and chitosan are the second most abundant natural biopolymers in the curst of the earth and have a long linear chain-like structure connected with β-d glucosidic linkage with the functionalizable surface groups as mentioned in this paper.
Abstract: Chitin and chitosan are the second most abundant natural biopolymers in the curst of the earth. These polysaccharide biopolymers have a long linear chain-like structure connected with β-d glucosidic linkage with the functionalizable surface groups. Because of the structural features, these biomaterials exhibit unique physical, chemical, mechanical and optical properties, which contributed to the tunable and outstanding properties such as low density, high porosity, renewability, natural biodegradability, and environmental friendliness, etc. Chitin was synthesized via mechanical, chemical, chemo-mechanical, and eco-friendly biological methods and the deacetylation of the synthesized chitin carried for the preparation of chitosan. With the chemical modification used for the preparation of chitosan, there occurs some minor change in characteristics; however, most of the properties were relatable due to major similarities in the microstructures. The inherent antibacterial, non-toxic, and biodegradable properties with the ease of processibility of both polymer has the potential to become a successful alternative to its synthetic counterparts for energy and environmental applications. However, the poor mechanical and thermal properties in comparison to the conventional alternatives have restricted its widespread applications. This review addresses various areas such as extraction techniques of chitin and synthesis of chitosan, discussion of the common characteristics of both polymers together such as crystallinity, thermal properties, mechanical properties, hydrophilicity, and surface charge. Moreover, this review paper also addresses the common functionalization techniques for both polymer and the use of both unmodified chitin and chitosan along with their derivatives in environmental and energy applications such as air pollution, heavy metal adsorption, dye adsorption, biosensors, EMI shielding, fuel cell, solar cell, lithium-ion batteries, and biofuels.
54 citations
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TL;DR: Chitin is insoluble in most common solvents, whereas chitosan dissolves in many common aqueous acid solutions and has good film and fiber forming properties.
Abstract: Chitin is a structural polysaccharide widely found in nature. It occurs as highly ordered microfibrils in many species such as yeast, fungi, insects, and marine invertebrates. Chitin is a homopolymer of 1-4 linked 2-acetamido-2-deoxy-β-d-glucopyranose, although some of the glucopyranose residues are deacetylated and occur as 2-amino-2-deoxy-β-d-glucopyranose. When chitin is deacetylated to more than 50% of the free amine form, it is referred to as chitosan. Biopolymerization of chitin is by the activated monomer N-acetyl-uridine diphosphate-glucosamine by synthase enzymes. The isolation of chitin is commonly from the shell fish waste of the shrimp and crab industries. Chitin is insoluble in most common solvents, whereas chitosan dissolves in many common aqueous acid solutions. Industrially, chitin is mainly used as a powder and as a precursor to chitosan. Applications of chitosan are found in many primary industries such as agriculture, paper, textiles, and wastewater treatment. Chitosan has good film and fiber forming properties. Many medical and pharmaceutical uses of chitosan have been described. It has also become a popular nutritional dietary additive.
Keywords:
chitin;
chitosan;
exoskeleton;
synthase enzyme;
chitinase;
chitosanase;
unit cell;
polyelectrolyte;
grafting;
film;
fiber;
gel;
antifungal;
ion removal;
chelation;
biodegradable;
biopolymer;
microfibril;
nontoxic;
amine;
amide;
oligomer
46 citations
TL;DR: In this paper, the authors used polysaccharide chitin to fabricate the hydrogel film for inducing the impaired sciatic nerve regeneration through incorporating the conductive poly(3,4-ethylenedioxythiophene) nanoparticles and modifying with cell adhesive tetrapeptide Cys-Arg-Gly-Asp (CRGD) (ChT-PEDOT-p).
Abstract: The nerve guidance conduit (NGC) is a promising clinical strategy for regenerating the critical-sized peripheral nerve injury. In this study, the polysaccharide chitin is used to fabricate the hydrogel film for inducing the impaired sciatic nerve regeneration through incorporating the conductive poly(3,4-ethylenedioxythiophene) nanoparticles (PEDOT NPs) and modifying with cell adhesive tetrapeptide Cys-Arg-Gly-Asp (CRGD) (ChT-PEDOT-p). The partial deacetylation process of chitin for exposing the amino groups is performed to (i) improve the electrostatic interaction between chitin and the negatively charged PEDOT for enhancing the composite hydrogel strength and (ii) offer the active sites for peptide modification. The as-prepared hydrogel remarkably promotes the in vitro RSC-96 cell adhesion and proliferation, as well as the Schwann cell activity-related gene S100, NF-200, and myelin basic protein (MBP) expression. Function of gastrocnemius muscle and thickness of myelinated axon in chitin/PEDOT groups are analogous to the autograft in 10 mm rat sciatic nerve defect. Immunofluorescence, immunohistochemistry, western blotting, and toluidine blue staining analyses on the regenerated sciatic nerve explain that the attachment and proliferation enhancement of Schwann cells and angiogenesis are the vital factors for the chitin/PEDOT composite to facilitate the nerve regeneration. This work provides an applicable chitin-based NGC material for accelerating the peripheral nerve restoration.
43 citations
25 Dec 2021
TL;DR: In this paper, a review of cellulose, chitin, and chitosan polysaccharides is presented, showing that their related structural features lead to biopolymer dissolution in common solvents such as ionic liquids.
Abstract: In this review we describe recent advances of biocomposites consisting of cellulose, chitin, and chitosan. These polysaccharides are very important because they are abundant and renewable resources. As such, they significantly contribute to the development of sustainable processing of bioactive and biodegradable materials since there is an increased concern about the sustainability of synthetic polymers, leading to increased presence of microplastics in the environment. First, we briefly describe the molecular structures of cellulose, chitin, and chitosan. Our objective is to show that their related structural features lead to biopolymer dissolution in common solvents such as ionic liquids. We also address the dissolution mechanisms, biopolymer-solvent interactions, and solvent properties required to dissolve these biopolymers. Mutual solvents for of cellulose, chitin, and chitosan allow composite preparation via solution mixing which is advantageous with regard to processing complexity and costs. Thus, we present preparation, properties and application of cellulose/chitin/chitosan biocomposites in various physical forms, such as (nano)fibers, films, membranes, and hydrogels.
39 citations
TL;DR: The insect-based chitin, its derivatives and their complexes with hyaluronic acid and lignin, as well as with other chit in-derived compounds, may be considered a new appropriate potential polymer to be used in cosmetic and cosmeceutical fields.
Abstract: Chitin and its derivatives are attracting great interest in cosmetic and cosmeceutical fields, thanks to their antioxidant and antimicrobial properties, as well as their biocompatibility and biodegradability. The classical source of chitin, crustacean waste, is no longer sustainable and fungi, a possible alternative, have not been exploited at an industrial scale yet. On the contrary, the breeding of bioconverting insects, especially of the Diptera Hermetia illucens, is becoming increasingly popular worldwide. Therefore, their exoskeletons, consisting of chitin as a major component, represent a waste stream of facilities that could be exploited for many applications. Insect chitin, indeed, suggests its application in the same fields as the crustacean biopolymer, because of its comparable commercial characteristics. This review reports several cosmetic and cosmeceutical applications based on chitin and its derivatives. In this context, chitin nanofibers and nanofibrils, produced from crustacean waste, have proved to be excellent cosmeceutical active compounds and carriers of active ingredients in personal care. Consequently, the insect-based chitin, its derivatives and their complexes with hyaluronic acid and lignin, as well as with other chitin-derived compounds, may be considered a new appropriate potential polymer to be used in cosmetic and cosmeceutical fields.
39 citations
TL;DR: Insects serve as an alternative source of chitin, which forms up to 40% of their exoskeleton, and can enhance each other's biological activity, providing a wide range of potential applications.
38 citations
01 Jan 2021
TL;DR: The structure of chitin is found to be intrinsically heterogeneous, with peak multiplicity detected in each sample and distinct fingerprints observed across fungal species, and the deacetylated form, chitosan, was found to resemble a relaxed two-fold helix conformation as mentioned in this paper.
Abstract: Chitin is a major carbohydrate component of the fungal cell wall and a promising target for novel antifungal agents. However, it is technically challenging to characterize the structure of this polymer in native cell walls. Here, we recorded and compared 13C chemical shifts of chitin using isotopically enriched cells of six Aspergillus, Rhizopus, and Candida strains, with data interpretation assisted by principal component analysis (PCA) and linear discriminant analysis (LDA) methods. The structure of chitin is found to be intrinsically heterogeneous, with peak multiplicity detected in each sample and distinct fingerprints observed across fungal species. Fungal chitin exhibits partial similarity to the model structures of α- and γ-allomorphs; therefore, chitin structure is not significantly affected by interactions with other cell wall components. Addition of antifungal drugs and salts did not significantly perturb the chemical shifts, revealing the structural resistance of chitin to external stress. In addition, the structure of the deacetylated form, chitosan, was found to resemble a relaxed two-fold helix conformation. This study provides high-resolution information on the structure of chitin and chitosan in their cellular contexts. The method is applicable to the analysis of other complex carbohydrates and polymer composites.
29 citations
TL;DR: Wang et al. as discussed by the authors developed double crosslinked chitin hydrogels by dissolving chitins in KOH/urea aqueous solution with freezing-thawing process, then using KH560 as cross-linking agent and coagulating in ethanol solution at low temperature.
TL;DR: In this article, a cellulose nanofibrilated fiber (CNF) was isolated from the textile waste cotton fabrics with combined supercritical carbon dioxide and high-pressure homogenization.
Abstract: Textile waste cellulose nanofibrillated fibre has been reported with excellent strength reinforcement ability in other biopolymers. In this research cellulose nanofibrilated fibre (CNF) was isolated from the textile waste cotton fabrics with combined supercritical carbon dioxide and high-pressure homogenisation. The isolated CNF was used to enhance the polylactic acid/chitin (PLA/chitin) properties. The properties enhancement effect of the CNF was studied by characterising the PLA/chitin/CNF biocomposite for improved mechanical, thermal, and morphological properties. The tensile properties, impact strength, dynamic mechanical analysis, thermogravimetry analysis, scanning electron microscopy, and the PLA/chitin/CNF biocomposite wettability were studied. The result showed that the tensile strength, elongation, tensile modulus, and impact strength improved significantly with chitin and CNF compared with the neat PLA. Furthermore, the scanning electron microscopy SEM (Scanning Electron Microscopy) morphological images showed uniform distribution and dispersion of the three polymers in each other, which corroborate the improvement in mechanical properties. The biocomposite's water absorption increased more than the neat PLA, and the contact angle was reduced. The results of the ternary blend compared with PLA/chitin binary blend showed significant enhancement with CNF. This showed that the three polymers' combination resulted in a better material property than the binary blend.
TL;DR: The viscosity of carboxymethyl chitin decreased rapidly at the initial stages when subjected to chit inase hydrolysis, which indicates that the chitInase acts in an endosplitting pattern.
Abstract: The chitinase-producing bacteria Paenibacillus sp. was isolated from soil samples. The chitinase was purified successively by ammonia sulfate fractional precipitation followed by chromatography on DEAE 52-cellulose column and then on Sephadex G-75 column. The chitinase has a molecular weight of ca. 30 kDa as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) electrophoresis. Its optimum pH is 4.5, and its optimum temperature is 50 °C with colloidal chitin as a substrate. The enzyme is stable below 45 °C and in pH ranges between 4.5 and 5.5. It is activated by glucosamine, glucose, N-acetylglucosamine, and metal ions including Ca2+ , Fe2+ , Fe3+ , and Ni2+ . It is inhibited by SDS, H2 O2 , ascorbic acid, Cu2+ , Mg2+ , Ba2+ , Sn2+ , Cr3+ , and K+ . With colloidal chitin as substrate, the Km and the Vmax of the chitinase are 4.28 mg/mL and 14.29 μg/(Min·mL), respectively, whereas the end products of the enzymatic hydrolysis are 14.33% monomer and 85.67% dimer of N-acetylglucosamine. The viscosity of carboxymethyl chitin decreased rapidly at the initial stages when subjected to chitinase hydrolysis, which indicates that the chitinase acts in an endosplitting pattern.
TL;DR: In this paper, the authors summarized the genes and pathways associated with the biosynthesis and degradation of chitins in crustaceans based on genomic analyses, and they found that chitin biosynthesis genes typically occur in single or two copies, whereas the degradation genes are all multiple copies.
Abstract: Chitin is among the most important components of the crustacean cuticular exoskeleton and intestinal peritrophic matrix. With the progress of genomics and sequencing technology, a large number of gene sequences related to chitin metabolism have been deposited in the GenBank database in recent years. Here, we summarized the genes and pathways associated with the biosynthesis and degradation of chitins in crustaceans based on genomic analyses. We found that chitin biosynthesis genes typically occur in single or two copies, whereas chitin degradation genes are all multiple copies. Moreover, the chitinase genes are significantly expanded in most crustacean genomes. The gene structure and expression pattern of these genes are similar to those of insects, albeit with some specific characteristics. Additionally, the potential applications of the chitin metabolism genes in molting regulation and immune defense, as well as industrial chitin degradation and production, are also summarized in this review.
TL;DR: In this article, the authors examined the role of candidate effector genes in the infection of melon (Cucumis melo L.) plants, using gene expression analysis, RNAi silencing assays, protein modeling and protein-ligand predictions, enzymatic assays and protein localization studies.
Abstract: In plants, chitin-triggered immunity is one of the first lines of defense against fungi, but phytopathogenic fungi have developed different strategies to prevent the recognition of chitin. Obligate biotrophs such as powdery mildew fungi suppress the activation of host responses; however, little is known about how these fungi subvert the immunity elicited by chitin. During epiphytic growth, the cucurbit powdery mildew fungus Podosphaera xanthii expresses a family of candidate effector genes comprising nine members with an unknown function. In this work, we examine the role of these candidates in the infection of melon (Cucumis melo L.) plants, using gene expression analysis, RNAi silencing assays, protein modeling and protein-ligand predictions, enzymatic assays, and protein localization studies. Our results show that these proteins are chitinases that are released at pathogen penetration sites to break down immunogenic chitin oligomers, thus preventing the activation of chitin-triggered immunity. In addition, these effectors, designated effectors with chitinase activity (EWCAs), are widely distributed in pathogenic fungi. Our findings reveal a mechanism by which fungi suppress plant immunity and reinforce the idea that preventing the perception of chitin by the host is mandatory for survival and development of fungi in plant environments.
TL;DR: The residual shell obtained after the hydrolysis of Acetes shrimp was used for the extraction of chitin by combining enzymatic and chemical treatments and showed that the protein removal efficiency increases with the increase in DH and the maximum deproteinzation was achieved at 30 % DH.
TL;DR: Chitin is the most abundant marine biopolymer, being recovered during the shell biorefining of crustacean shell waste as mentioned in this paper, and it displays a poor reactivity and solubility in most s...
Abstract: Chitin is the most abundant marine biopolymer, being recovered during the shell biorefining of crustacean shell waste. In its native form, chitin displays a poor reactivity and solubility in most s...
TL;DR: In this article, the authors measured the adsorption affinities of raw types of chitin and chitosan for approximately 30 types of micropollutants in neutral or ionic forms.
TL;DR: Modification to a chemical method of chitin synthesis from shrimp shells has been proposed through the application of high-frequency ultrasound for the production of biopolymers, which reduced the protein content as well as the particle size of Chitin.
TL;DR: In this article, chitin aerogel doped with nano-calcium carbonate (CaCO3/chitin Aerogel) was prepared by dissolving chitins in Na2 CO3/Ca (OH)2/urea system followed by epichlorohydrin (ECH) addition as a crosslinker and then freeze-drying of the hydrogel.
25 Dec 2021
TL;DR: In this paper, chitin was extracted from marine crustacean shell waste using traditional chemical methods (deproteinisation and demineralization) and its physicochemical and structural properties were characterized.
Abstract: In the present study, chitin was extracted from marine crustacean shell waste (shrimp, crab, squilla and lobster) using traditional chemical methods (deproteinisation and demineralization) and its physicochemical and structural properties were characterized. The chitin content of crustacean shell waste ranged from 17.50% to 23.75% on a dry weight basis. The molecular weight analyses revealed that the crustacean chitin showed low molecular weight. The results of X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FT-IR), Energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and thermogravimetry/differential thermal analysis (TG/DTA) confirmed that the α-chitins isolated from crustacean shell waste were similar to commercial crustacean chitin. The crystalline index value of the extracted chitin varied from 80.3% to 80.8%. The infrared spectroscopy analysis of the crustacean chitin exhibited two bands at around 1660 and 1620 cm−1. SEM analysis of the extracted chitin showed the nanofibre and nanopore structures. Additionally, thermal stability of the crustacean chitin was close to that of the commercial chitin. Therefore, the results of this study confirmed that the extracted chitin is in α-form.
TL;DR: This is the first example of ultrasound-assisted polymer analogues transformation of chitin unaccompanied by noticeable backbone degradation or deacetylation, and the obtained water-soluble azido chit in derivatives are characterized by high antibacterial activity, which is comparable with that of commercial antibiotics ampicillin and gentamicin.
TL;DR: In this paper, the authors investigated the carbohydrate content and composition of mealworms and the characteristics of mealworm chitin and chitosan, and they found that chitins were the key components of meal worm carbohydrate with a yield of 4.7%.
Abstract: Mealworm (Tenebrio molitor L.) is a classic edible insect with high nutritional value for substituting meats from vertebrates. While interest in mealworms has increased, the determination of carbohydrate constituents of mealworms has been overlooked. Thus, the aim of the present study was to investigate the carbohydrate content and composition of mealworms. In addition, the characteristics of mealworm chitin were determined as these were the major components of mealworm carbohydrate. The crude carbohydrate content of mealworms was 11.5%, but the total soluble sugar content was only 30% of the total carbohydrate content, and fructose was identified as the most abundant free sugar in mealworms. Chitin derivatives were the key components of mealworm carbohydrate with a yield of 4.7%. In the scanning electron microscopy images, a lamellar structure with α-chitin configuration was observed, and mealworm chitosan showed multiple pores on its surface. The overall physical characteristics of mealworm chitin and chitosan were similar to those of the commercial products derived from crustaceans. However, mealworm chitin showed a significantly softer texture than crustacean chitin with superior anti-inflammatory effects. Hence, mealworm chitin and chitosan could be employed as novel resources with unique advantages in industries.
TL;DR: In this article, the chitin deacetylase (CDA) family of Ustilago maydis has been studied and it was shown that certain combinations of mutations significantly affected virulence with reduced adherence, appressorium formation, penetration and activation of plant defenses.
Abstract: The biotrophic fungus Ustilago maydis harbors a chitin deacetylase (CDA) family of six active genes as well as one pseudogene which are differentially expressed during colonization. This includes one secreted soluble CDA (Cda4) and five putatively glycosylphosphatidylinositol (GPI)-anchored CDAs, of which Cda7 belongs to a new class of fungal CDAs. Here, we provide a comprehensive functional study of the entire family. While budding cells of U. maydis showed a discrete pattern of chitosan staining, biotrophic hyphae appeared surrounded by a chitosan layer. We purified all six active CDAs and show their activity on different chitin substrates. Single as well as multiple cda mutants were generated and revealed a virulence defect for mutants lacking cda7 We implicated cda4 in production of the chitosan layer surrounding biotrophic hyphae and demonstrated that the loss of this layer does not reduce virulence. By combining different cda mutations, we detected redundancy as well as specific functions for certain CDAs. Specifically, certain combinations of mutations significantly affected virulence concomitantly with reduced adherence, appressorium formation, penetration, and activation of plant defenses. Attempts to inactivate all seven cda genes simultaneously were unsuccessful, and induced depletion of cda2 in a background lacking the other six cda genes illustrated an essential role of chitosan for cell wall integrity.IMPORTANCE The basidiomycete Ustilago maydis causes smut disease in maize, causing substantial losses in world corn production. This nonobligate pathogen penetrates the plant cell wall with the help of appressoria and then establishes an extensive biotrophic interaction, where the hyphae are tightly encased by the plant plasma membrane. For successful invasion and development in plant tissue, recognition of conserved fungal cell wall components such as chitin by the plant immune system needs to be avoided or suppressed. One strategy to achieve this lies in the modification of chitin to chitosan by chitin deacetylases (CDAs). U. maydis has seven cda genes. This study reveals discrete as well as redundant contributions of these genes to virulence as well as to cell wall integrity. Unexpectedly, the inactivation of all seven genes is not tolerated, revealing an essential role of chitosan for viability.
TL;DR: In this article, Daphnia similis chitin and its derivative chitosan were prepared as immunostimulants to boost the immune response and determine the ability to control infectious disease caused by Vibrio alginolyticus in white shrimp, Litopenaeus vannamei.
TL;DR: In this paper, the authors used FTIR spectra and XRD patterns to characterize chitosan from locally available material for potential use in the biomedical field and found that chitin is also an important component of fish scales, insects and fungal cell walls.
Abstract: Of recent, immense attention has been given to chitosan in the biomedical field due to its valuable biochemical and physiological properties. Traditionally, the chief source of chitosan is chitin from crab and shrimp shells. Chitin is also an important component of fish scales, insects and fungal cell walls. Thus, the aim of this study was to isolate and characterize chitosan from locally available material for potential use in the biomedical field. Chitosan ash and nitrogen contents ranged from 1.55 to 3.5% and 6.6 to 7.0% respectively. Molecular weight varied from 291 to 348KDa. FTIR spectra revealed high degree of similarity between locally isolated chitosan and commercial chitosan with DD ranging from 77.8 to 79.1%. XRD patterns exhibited peaks at 2θ values of 19.5° for both mushroom and banana weevil chitosan while Nile perch scales chitosan registered 3 peaks at 2θ angles of 12.3°, 20.1° and 21.3° comparable to the established commercial chitosan XRD pattern. Locally isolated chitosan exhibited antimicrobial activity at a very high concentration. Ash content, moisture content, DD, FTIR spectra and XRD patterns revealed that chitosan isolated from locally available materials has physiochemical properties comparable to conventional chitosan and therefore it can be used in the biomedical field.
TL;DR: The main bioactive properties of COS are herein reviewed and the anti-inflammatory activity of three COS mixtures was assayed in murine macrophages after stimulation with lipopolysaccharides.
Abstract: Chitooligosaccharides (COS) are homo- or hetero-oligomers of D-glucosamine (GlcN) and N-acetyl-D-glucosamine (GlcNAc) that can be obtained by chitosan or chitin hydrolysis. Their enzymatic production is preferred over other methodologies (physical, chemical, etc.) due to the mild conditions required, the fewer amounts of waste and its efficiency to control product composition. By properly selecting the enzyme (chitinase, chitosanase or nonspecific enzymes) and the substrate properties (degree of deacetylation, molecular weight, etc.), it is possible to direct the synthesis towards any of the three COS types: fully acetylated (faCOS), partially acetylated (paCOS) and fully deacetylated (fdCOS). In this article, we review the main strategies to steer the COS production towards a specific group. The chemical characterization of COS by advanced techniques, e.g., high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and MALDI-TOF mass spectrometry, is critical for structure–function studies. The scaling of processes to synthesize specific COS mixtures is difficult due to the low solubility of chitin/chitosan, the heterogeneity of the reaction mixtures, and high amounts of salts. Enzyme immobilization can help to minimize such hurdles. The main bioactive properties of COS are herein reviewed. Finally, the anti-inflammatory activity of three COS mixtures was assayed in murine macrophages after stimulation with lipopolysaccharides.
TL;DR: In this article, potent protease and lactic acid-producing bacteria were screened and identified as Alcaligens faecalis S3 and Bacillus coagulans L2, respectively.
Abstract: Chemical extraction of chitin is very hazardous and costly which can be overwhelmed by microbial bioprocessing. In this study, potent protease and lactic acid-producing bacteria were screened and identified as Alcaligens faecalis S3 and Bacillus coagulans L2, respectively. Productions of protease and lactic acid by the respective bacterial strains were optimized. The shell of Litopenaeus vannamei was sequentially treated with the partially purified protease and lactic acid and the treatment conditions were optimized for betterment of chitin yield. Spectral characterization by SEM-EDS, IR, XRD, NMR, XPS and thermal characterization by TG and DTG analysis of the extracted chitin was made and compared with commercial one. It was revealed that both the chitin have similar characteristics. Therefore, it can be articulated that chitin can be extracted from crustacean shells in pure form by microbial bioprocessing which will be a good catch for biorefinary industries for chitin extraction through greener route.
TL;DR: In this paper, the authors integrate cultivation-dependent and independent approaches to shed light on the chitin processing potential within the microbiomes of marine sponges, octocorals, sediments, and seawater.
Abstract: Chitin ranks as the most abundant polysaccharide in the oceans yet knowledge of shifts in structure and diversity of chitin-degrading communities across marine niches is scarce. Here, we integrate cultivation-dependent and -independent approaches to shed light on the chitin processing potential within the microbiomes of marine sponges, octocorals, sediments, and seawater. We found that cultivatable host-associated bacteria in the genera Aquimarina, Enterovibrio, Microbulbifer, Pseudoalteromonas, Shewanella, and Vibrio were able to degrade colloidal chitin in vitro. Congruent with enzymatic activity bioassays, genome-wide inspection of cultivated symbionts revealed that Vibrio and Aquimarina species, particularly, possess several endo- and exo-chitinase-encoding genes underlying their ability to cleave the large chitin polymer into oligomers and dimers. Conversely, Alphaproteobacteria species were found to specialize in the utilization of the chitin monomer N-acetylglucosamine more often. Phylogenetic assessments uncovered a high degree of within-genome diversification of multiple, full-length endo-chitinase genes for Aquimarina and Vibrio strains, suggestive of a versatile chitin catabolism aptitude. We then analyzed the abundance distributions of chitin metabolism-related genes across 30 Illumina-sequenced microbial metagenomes and found that the endosymbiotic consortium of Spongia officinalis is enriched in polysaccharide deacetylases, suggesting the ability of the marine sponge microbiome to convert chitin into its deacetylated—and biotechnologically versatile—form chitosan. Instead, the abundance of endo-chitinase and chitin-binding protein-encoding genes in healthy octocorals leveled up with those from the surrounding environment but was found to be depleted in necrotic octocoral tissue. Using cultivation-independent, taxonomic assignments of endo-chitinase encoding genes, we unveiled previously unsuspected richness and divergent structures of chitinolytic communities across host-associated and free-living biotopes, revealing putative roles for uncultivated Gammaproteobacteria and Chloroflexi symbionts in chitin processing within sessile marine invertebrates. Our findings suggest that differential chitin degradation pathways, utilization, and turnover dictate the processing of chitin across marine micro-niches and support the hypothesis that inter-species cross-feeding could facilitate the co-existence of chitin utilizers within marine invertebrate microbiomes. We further identified chitin metabolism functions which may serve as indicators of microbiome integrity/dysbiosis in corals and reveal putative novel chitinolytic enzymes in the genus Aquimarina that may find applications in the blue biotechnology sector.