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Found 1 structure.
Displayed structure 1
| -4)-b-D-GlcpN(%)Ac-(1- | Show graphically |
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Structure type: structural motif or average structure
Trivial name: chitosan
Compound class: O-polysaccharide, cell wall polysaccharide, glucan, polysaccharide
Contained glycoepitopes: IEDB_135813,IEDB_137340,IEDB_141807,IEDB_151531,IEDB_153212,IEDB_241099,IEDB_423114,IEDB_423150,SB_74,SB_85
Fed-batch fermentation was used for biomass and fungal chitosan production by Aspergillus terreus (BCRC 32068) grown in a potato dextrose agar medium. The polysaccharides were extracted by an alkali-acid treatment, and structural investigations by X-ray diffraction, Fourier transform infrared analysis, and viscosity and thermal analysis were done. A high level of chitosan was extracted from A. terreus; this implied that it was feasible to produce chitosan from industrial waste mycelia. Fungal chitosan derived from A. terreus showed the highest adsorption capacity for Sn(II). The order of Sn(II) adsorption capacity for these chitosanaceous materials was Fungal chitosan>Chitin>Biomass. Fungal chitosan derived from A. terreus was well correlated with Langmuir's isotherm model. The maximum capacity for Sn(II) sorption deduced from the use of the Langmuir isotherm equation was 303 mg/g; this was significantly higher than that of A. terreus. Fungal chitosan is an easy and cost-effective material for the abatement of pollution.
polysaccharides, Adsorption, biopolymers and renewable polymers
Publication DOI: 10.1002/app.40436Chitin is an essential component of the cell wall of Cryptococcus neoformans conferring structural rigidity and integrity under diverse environmental conditions. Chitin deacetylase genes encode the enyzmes (chitin deacetylases [Cdas]) that deacetylate chitin, converting it to chitosan. The functional role of chitosan in the fungal cell wall is not well defined, but it is an important virulence determinant of C. neoformans Mutant strains deficient in chitosan are completely avirulent in a mouse pulmonary infection model. C. neoformans carries genes that encode three Cdas (Cda1, Cda2, and Cda3) that appear to be functionally redundant in cells grown under vegetative conditions. Here we report that C. neoformans Cda1 is the principal Cda responsible for fungal pathogenesis. Point mutations were introduced in the active site of Cda1 to generate strains in which the enzyme activity of Cda1 was abolished without perturbing either its stability or localization. When used to infect CBA/J mice, Cda1 mutant strains produced less chitosan and were attenuated for virulence. We further demonstrate that C. neoformans Cda genes are transcribed differently during a murine infection from what has been measured in vitro IMPORTANCE Cryptococcus neoformans is unique among fungal pathogens that cause disease in a mammalian host, as it secretes a polysaccharide capsule that hinders recognition by the host to facilitate its survival and proliferation. Even though it causes serious infections in immunocompromised hosts, reports of infection in hosts that are immunocompetent are on the rise. The cell wall of a fungal pathogen, its synthesis, composition, and pathways of remodelling are attractive therapeutic targets for the development of fungicides. Chitosan, a polysaccharide in the cell wall of C. neoformans is one such target, as it is critical for pathogenesis and absent in the host. The results we present shed light on the importance of one of the chitin deacetylases that synthesize chitosan during infection and further implicates chitosan as being a critical factor for the pathogenesis of C. neoformans.
chitosan, fungal virulence, catalytic site, cell wall localization, chitin deacetylase, metal binding site
NCBI PubMed ID: 30459196This study was devoted to polysaccharides extraction (chitin and chitosan) from Penicillium camembertii cell wall. A culture on solid medium was adopted under carefully selected conditions, appropriate to mycelium growth: duration 6 days, medium YPGA and pH 5. The temperature was adjusted (20 °C to 28 °C) in order to study the effect of temperature on chitin/chitosan production. Biomass decreased with increasing temperatures: 13 g/L at 20 °C and 11.6 g/L at 28 °C. For all tested temperatures, the yields of insoluble alkaline fractions (AIM) were almost identical (200 mg/g). The solubility of fractions in 2% acetic acid allowed obtaining two fractions: an insoluble fraction (AcIM) with 18% of maximum yield and soluble fraction (AcSM) with 1% yield. The SEM micrographs of AcIM fractions were similar to AIM fractions. These showed a compact structure different from commercial chitin. The presence of chitin in P. Camembertii cultured in YPGA medium was also confirmed by ATR spectroscopy.
chitin, Biomass, free chitosan, Penicillium camembertii, YPGA
NCBI PubMed ID: 31004649Conventional piezoelectric materials from piezoceramic and polymer are non-renewable and could be toxic in nature, which limit its application in biomedical application. Chitosan, which is a natural polysaccharide, has the potential to be used as piezoelectric biomaterial which may provide the solution for toxicity, non-biodegradability and non-biocompatibility issues of conventional piezoelectric materials. Chitosan may be produced sustainably through extraction from fungal cell walls. This study aims to characterize chitosan extracted from fungi Aspergillus oryzae for piezoelectric application. A. oryzae was cultivated on modified Sabouraud dextrose broth medium. Alkaline treatment was performed on fungal biomass using 1 M NaOH for extraction and deacetylation of chitosan at 100 °C for 1 hour. Fourier transform infrared spectroscopy results showed that the broad absorption band that corresponds to hydrogen bonded O-H stretching vibrations overlapped with N-H stretching band. X-ray diffraction analysis confirmed the semicrystalline nature of the chitosan sample. Piezoelectric properties can be attributed to intrinsic molecular polarization arising from the noncentrosymmetric crystal structure.
chitosan, Aspergillus oryzae, piezoelectric material
Publication DOI: 10.1088/1757-899X/778/1/012034Chitin, chitosan and their complexes with β-glucan (chitin–glucan complex, CGC, and chitosan–glucan complex, ChGC) are value-added polysaccharides extracted from the cell-walls of many fungi. Commercial chitin and its deacetylated form, chitosan, are currently obtained from marine waste material, mostly animal sources (crustaceans and marine invertebrates), through harsh chemical procedures that have low reproducibility due to the variability of the composition of the sources and their seasonal character. These disadvantages are overcome by using fungi as sources of chitinous polymers. The extraction of chitin/chitosan from fungi cell-walls has the great advantage of yielding products with stable composition and properties, using simpler procedures, with the added benefit of also generating CGC and ChGC, two copolymers that combine the proven properties of chitin/chitosan with those of β-glucans. Over the last decades, fungal chitinous polymers have been the focus of extensive research that included optimization of the cultivation conditions of a wide range of species and the development of optimized extraction, purification and characterization techniques, as well as the demonstration of the biopolymers' biological properties, which include immunomodulatory, anticancer, antioxidant and antimicrobial activity. Given these properties, several attempts were made to develop applications for them in areas ranging from biomedicine and pharmaceuticals to food and agriculture. Despite their wide range of proven functional properties that include the ability to form different polymeric structures, as well as biological activity, fungal chitinous biopolymers are still underexplored. Nevertheless, these biopolymers hold great potential for development into valuable products or applications that are surely worth further investigation.
fungi, chitosan, chitin, cell-wall polysaccharides, chitin–glucan complex (CGC), chitosan–glucan complex (ChGC)
Publication DOI: 10.1002/jctb.6325Candida auris has emerged as a multidrug-resistant nosocomial pathogen over the last decade. Outbreaks of the organism in health care facilities have resulted in life-threatening invasive candidiasis in over 40 countries worldwide. Resistance by C. auris to conventional antifungal drugs such as fluconazole and amphotericin B means that alternative therapeutics must be explored. As such, this study served to investigate the efficacy of a naturally derived polysaccharide called chitosan against aggregative (Agg) and nonaggregative (non-Agg) isolates of C. auris in vitro and in vivo. In vitro results indicated that chitosan was effective against planktonic and sessile forms of Agg and non-Agg C. auris In a Galleria mellonella model to assess C. auris virulence, chitosan treatment was shown to ameliorate killing effects of both C. auris phenotypes (NCPF 8973 and NCPF 8978, respectively) in vivo Specifically, chitosan reduced the fungal load and increased survival rates of infected Galleria, while treatment alone was nontoxic to the larvae. Finally, chitosan treatment appeared to induce a stress-like gene expression response in NCPF 8973 in the larvae likely arising from a protective response by the organism to resist antifungal activity of the compound. Taken together, results from this study demonstrate that naturally derived compounds such as chitosan may be useful alternatives to conventional antifungals against C. auris.
aggregates, therapeutics, chitosan, Candida auris, Galleria mellonella
NCBI PubMed ID: 32482674Chitin and chitosan are two related polysaccharides that provide important structural stability to fungal cell walls. Often embedded deeply within the cell wall structure, these molecules anchor other components at the cell surface. Chitin-directed organization of the cell wall layers allows the fungal cell to effectively monitor and interact with the external environment. For fungal pathogens, this interaction includes maintaining cellular strategies to avoid excessive detection by the host innate immune system. In turn, mammalian and plant hosts have developed their own strategies to process fungal chitin, resulting in chitin fragments of varying molecular size. The size-dependent differences in the immune activation behaviors of variably sized chitin molecules help to explain how chitin and related chitooligomers can both inhibit and activate host immunity. Moreover, chitin and chitosan have recently been exploited for many biomedical applications, including targeted drug delivery and vaccine development.
NCBI PubMed ID: 31807896The fungal cell wall serves as the interface between the cell and the environment. Fungal cell walls are composed largely of polysaccharides, primarily glucans and chitin, though in many fungi stress-resistant cell types elaborate additional cell wall structures. Here, we use solid-state nuclear magnetic resonance spectroscopy to compare the architecture of cell wall fractions isolated from Saccharomyces cerevisiae spores and Cryptococcus neoformans melanized cells. The specialized cell walls of these two divergent fungi are highly similar in composition. Both use chitosan, the deacetylated derivative of chitin, as a scaffold on which a polyaromatic polymer, dityrosine and melanin, respectively, is assembled. Additionally, we demonstrate that a previously identified but uncharacterized component of the S. cerevisiae spore wall is composed of triglycerides, which are also present in the C. neoformans melanized cell wall. Moreover, we identify a tyrosine-derived constituent in the C. neoformans wall that, although it is not dityrosine, is a non-pigment constituent of the cell wall. The similar composition of the walls of these two phylogenetically distant species suggests that triglycerides, polyaromatics, and chitosan are basic building blocks used to assemble highly stress-resistant cell walls and the use of these constituents may be broadly conserved in other fungal species.
chitosan, Saccharomyces cerevisiae, chitin, fungal cell wall, solid-state NMR, Cryptococcus neoformans, melanin, macromolecular assembly, dityrosine, triglycerides
NCBI PubMed ID: 33271921Cryptococcus neoformans and Cryptococcus gattii are two species complexes in the large fungal genus Cryptococcus and are responsible for potentially lethal disseminated infections. These two complexes share several phenotypic traits, such as production of the protective compound melanin. In C. neoformans, the pigment associates with key cellular constituents that are essential for melanin deposition within the cell wall. Consequently, melanization is modulated by changes in cell-wall composition or ultrastructure. However, whether similar factors influence melanization in C. gattii is unknown. Herein, we used transmission EM, biochemical assays, and solid-state NMR spectroscopy of representative isolates and "leaky melanin" mutant strains from each species complex to examine the compositional and structural factors governing cell-wall pigment deposition in C. neoformans and C. gattii. The principal findings were the following. 1) C. gattii R265 had an exceptionally high chitosan content compared with C. neoformans H99; a rich chitosan composition promoted homogeneous melanin distribution throughout the cell wall but did not increase the propensity of pigment deposition. 2) Strains from both species manifesting the leaky melanin phenotype had reduced chitosan content, which was compensated for by the production of lipids and other nonpolysaccharide constituents that depended on the species or mutation. 3) Changes in the relative rigidity of cell-wall chitin were associated with aberrant pigment retention, implicating cell-wall flexibility as an independent variable in cryptococcal melanin assembly. Overall, our results indicate that cell-wall composition and molecular architecture are critical factors for the anchoring and arrangement of melanin pigments in both C. neoformans and C. gattii species complexes.
Molecular Structure, cell wall, polysaccharides, virulence factor, opportunistic pathogen, nuclear magnetic resonance (NMR), fungi, Cryptococcus, solid-state NMR, melanin
NCBI PubMed ID: 31896575The human gut microbiota has been revealed in recent years as a factor that plays a decisive role in the maintenance of human health, as well as in the development of many non-communicable diseases. This microbiota can be modulated by various dietary factors, among which complex carbohydrates have a great influence. Although most complex carbohydrates included in the human diet come from vegetables, there are also options to include complex carbohydrates from non-vegetable sources, such as chitin and its derivatives. Chitin, and its derivatives such as chitosan can be obtained from non-vegetable sources, the best being insects, crustacean exoskeletons and fungi. The present review offers a broad perspective of the current knowledge surrounding the impacts of chitin and its derived polysaccharides on the human gut microbiota and the profound need for more in-depth investigations into this topic. Overall, the effects of whole insects or meal on the gut microbiota have contradictory results, possibly due to their high protein content. Better results are obtained for the case of chitin derivatives, regarding both metabolic effects and effects on the gut microbiota composition.
polysaccharides, insect, gut microbiota, prebiotic, chitosan, chitin, crustacean
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