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Chitin

About: Chitin is a research topic. Over the lifetime, 6590 publications have been published within this topic receiving 253993 citations.


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Journal ArticleDOI
TL;DR: The present review discusses the potential bioextraction of chitosan from fungal, insect, and crustacean as well as its superior physico-chemical properties and highlighted new perspectives on the production of Chitin and deacetylated chitan from different sources with the concomitant reduction of the environmental impact.
Abstract: The natural biopolymer chitin and its deacetylated product chitosan are found abundantly in nature as structural building blocks and are used in all sectors of human activities like materials science, nutrition, health care, and energy Far from being fully recognized, these polymers are able to open opportunities for completely novel applications due to their exceptional properties which an economic value is intrinsically entrapped On a commercial scale, chitosan is mainly obtained from crustacean shells rather than from the fungal and insect sources Significant efforts have been devoted to commercialize chitosan extracted from fungal and insect sources to completely replace crustacean-derived chitosan However, the traditional chitin extraction processes are laden with many disadvantages The present review discusses the potential bioextraction of chitosan from fungal, insect, and crustacean as well as its superior physico-chemical properties The different aspects of fungal, insects, and crustacean chitosan extraction methods and various parameters having an effect on the yield of chitin and chitosan are discussed in detail In addition, this review also deals with essential attributes of chitosan for high value-added applications in different fields and highlighted new perspectives on the production of chitin and deacetylated chitosan from different sources with the concomitant reduction of the environmental impact

179 citations

Journal ArticleDOI
TL;DR: It is concluded that damage to the cell wall is caused by excessive chitinase activity at acidic pH, which can normally be repaired through chit in synthesis by Chs1, and the latter emerges as an auxiliary or emergency enzyme.
Abstract: Previously, we showed that chitin synthase 2 (Chs2) is required for septum formation in Saccharomyces cerevisiae, whereas chitin synthase 1 (Chs1) does not appear to be an essential enzyme. However, in strains carrying a disrupted CHS1 gene, frequent lysis of buds is observed. Lysis occurs after nuclear separation and appears to result from damage to the cell wall, as indicated by osmotic stabilization and by a approximately 50-nm orifice at the center of the birth scar. Lysis occurs at a low pH and is prevented by buffering the medium above pH 5. A likely candidate for the lytic system is a previously described chitinase that is probably involved in cell separation. The chitinase has a very acidic pH optimum and a location in the periplasmic space that exposes it to external pH. Accordingly, allosamidin, a specific chitinase inhibitor, substantially reduced the number of lysed cells. Because the presence of Chs1 in the cell abolishes lysis, it is concluded that damage to the cell wall is caused by excessive chitinase activity at acidic pH, which can normally be repaired through chitin synthesis by Chs1. The latter emerges as an auxiliary or emergency enzyme. Other experiments suggest that both Chs1 and Chs2 collaborate in the repair synthesis of chitin, whereas Chs1 cannot substitute for Chs2 in septum formation.

178 citations

Journal ArticleDOI
TL;DR: A holistic view of the complex molecular self-assembling structure of keratin and knowledge about enzymatic and boosting factors needed for keratin breakdown have been used to formulate a hypothesis for mode of action of the LPMOs in keratin decomposition and for a model for degradation of Keratin in nature.
Abstract: Discovery of keratin-degrading enzymes from fungi and bacteria has primarily focused on finding one protease with efficient keratinase activity. Recently, an investigation was conducted of all keratinases secreted from a fungus known to grow on keratinaceous materials, such as feather, horn, and hooves. The study demonstrated that a minimum of three keratinases is needed to break down keratin, an endo-acting, an exo-acting, and an oligopeptide-acting keratinase. Further, several studies have documented that disruption of sulfur bridges of the keratin structure acts synergistically with the keratinases to loosen the molecular structure, thus giving the enzymes access to their substrate, the protein structure. With such complexity, it is relevant to compare microbial keratin decomposition with the microbial decomposition of well-studied polymers such as cellulose and chitin. Interestingly, it was recently shown that the specialized enzymes, lytic polysaccharide monoxygenases (LPMOs), shown to be important for breaking the recalcitrance of cellulose and chitin, are also found in keratin-degrading fungi. A holistic view of the complex molecular self-assembling structure of keratin and knowledge about enzymatic and boosting factors needed for keratin breakdown have been used to formulate a hypothesis for mode of action of the LPMOs in keratin decomposition and for a model for degradation of keratin in nature. Testing such hypotheses and models still needs to be done. Even now, the hypothesis can serve as an inspiration for designing industrial processes for keratin decomposition for conversion of unexploited waste streams, chicken feather, and pig bristles into bioaccessible animal feed.

178 citations

Journal ArticleDOI
TL;DR: Chitin microspheres constructed using a "bottom-up" fabrication pathway showed a high attachment efficiency and the great potential of the NCM for 3D cell microcarriers, indicating the great possible of the nanofibrous surface and the inherent biocompatibility of chitin.
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.

178 citations

Journal ArticleDOI
TL;DR: A temporal analysis of cell wall changes was performed following a shift of the mutants from permissive to nonpermissive pH, and it is suggested that the Phr proteins process beta-1,3-glucans and make available acceptor sites for the attachment of beta- 1,6- glucans.
Abstract: PHR1 and PHR2 encode putative glycosylphosphatidylinositol-anchored cell surface proteins of the opportunistic fungal pathogen Candida albicans. These proteins are functionally related, and their expression is modulated in relation to the pH of the ambient environment in vitro and in vivo. Deletion of either gene results in a pH-conditional defect in cell morphology and virulence. Multiple sequence alignments demonstrated a distant relationship between the Phr proteins and beta-galactosidases. Based on this alignment, site-directed mutagenesis of the putative active-site residues of Phr1p and Phr2p was conducted and two conserved glutamate residues were shown to be essential for activity. By taking advantage of the pH-conditional expression of the genes, a temporal analysis of cell wall changes was performed following a shift of the mutants from permissive to nonpermissive pH. The mutations did not grossly affect the amount of polysaccharides in the wall but did alter their distribution. The most immediate alteration to occur was a fivefold increase in the rate of cross-linking between beta-1,6-glycosylated mannoproteins and chitin. This increase was followed shortly thereafter by a decline in beta-1,3-glucan-associated beta-1, 6-glucans and, within several generations, a fivefold increase in the chitin content of the walls. The increased accumulation of chitin-linked glucans was not due to a block in subsequent processing as determined by pulse-chase analysis. Rather, the results suggest that the glucans are diverted to chitin linkage due to the inability of the mutants to establish cross-links between beta-1,6- and beta-1,3-glucans. Based on these and previously published results, it is suggested that the Phr proteins process beta-1,3-glucans and make available acceptor sites for the attachment of beta-1,6-glucans.

178 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023434
2022868
2021271
2020354
2019333
2018271