Fungi chitin from

Chitosan and its derivatives are the most widely used cationic polymeric excipients. Chitosan consists of (31—>4 D-glucosamine units and is derived by the deacetylation of chitin from insects, crustaceans and fungi. It interacts ionically with the anionic substructures of sialic acid residues on the mucus layer. Chitosans are rapidly hydrated in a low pH environment like the gastric fluid and do not swell above pH levels of 6.5, exhibiting no more mucoadhesion. 

Gage and Tyler (1991) stated that fungi, as prominent heterotrophic organisms in the oceans, are transported passively from the surface to the deep sea by rapidly sinking water masses in the Arctic and Antarctic regions and/or by attachment to sinking particulate substrate (Van Uden Fell, 1968 Kohlmeyer Kohlmeyer, 1979). Several substrates, such as wood, particulate organic matter, or chitin from the exoskeleton of... 

Methods used for the preparation of chitin from lobster shell are equally applicable to fungi. Successive extraction with aqueous acid and hot, aqueous alkali leaves chitin as an insoluble residue. 

Chitin is undoubtedly the most abundant animal polysaccharide on earth. It constitutes the basic element of the exo-skeleton of insects and crustaceans, but it is also found in the outer skin of fungi. Chitin is a regular linear polymer whose structure differs from that of cellulose by the presence of Al-methylamide moieties instead of the hydroxyl groups at C2 (Fig. 1.17). Given the susceptibility of this function to hydrolysis, chitin often bears a small fraction of monomer units in the form of primary amino groups resulting from that chemical modification. 

Momilactones arise from GGPP via 9,pH-labdadienyl pyrophosphate (66) and 9-3H-pimara-7,15-diene (67), whereas oryzalexins arise via copalyl pyrophosphate (35) and sandaracopimaridiene (36). Both groups of diterpenes appear to be synthesized in the cytosol. Only kaurene is found in tissue not attacked by fungi. Chitin proved to be the best elicitor of momilactones in cell culture (West et al., 1990). Chitinase probably breaks down the chitin to active fragments (West et al., 1990). Both types of phytoalexins from rice are probably important in disease resistance, but the relative importance of each has not been assessed (West et al., 1990). 

Liao W, Liu Y, Frear C, Chen SL. (2008). Co-production of fumaric acid and chitin from a nitrogen rich lignocellulosic material dairy manure using a pelletized filamentous fungi Rhizopus oryzae ATTC 20344. Bioresour Technol, 96, 2026-2032. 

Indeed, the use of biological treatment instead of chemical treatment for the isolation of chitin from crustacean shells as well as for production of chitosan will substantially reduce environmental pollution. The use of chitin deacetylase for the preparation of chitosan polymers and oligomers offers the possibility to develop an enzymatic process that could potentially overcome most of the drawbacks discussed earlier [59]. As shown in Fig. 4, chitin deacetylase (CDA EC 3.5.1.41) catalyzes the hydrolysis of A-acetamido bonds in chitin to produce chitosan. The presence of this enzyme has been reported in several fungi and insect species [60-68]. 

Teng WL, Khor E, Tan TK et al (2001) Concurrent production of chitin from shrimp shells and fungi. Carbohydr Res 332 305-316... 

Chitin is a polysaccharide structurally and functionally related to cellulose. The structure is derived from that of cellulose by replacing one of the hydroxyl groups on each monosaccharide unit by an acetamido group, —NHCOCH3. Chitin is the structural polysaccharide of lower plants, such as fungi, and of invertebrates, particularly arthropods. It is the second most abundant organic substance on Earth. 

Thus chitin is abunckmt in the sea, in diatom blooms and in the zooplankton, most notably in the shoals of krill and on the land, in invertebrates and in fungi in the soil. Potential industrial sources are wastes from shrimps and crabs, krill, squid, clams and oysters, and fungal fermentations (13). The krUl fishery alone produces 3000 tons per year, currently going to waste. 

Chitin, a homopolymer from pi 4-linked N-acetylglucosamine, is the most important structural substance in insect and crustacean shells, and is thus the most common animal polysaccharide. It also occurs in the cell wall of fungi. 

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