Fungal cell-wall polysaccharides

Production, Properties and Applications of Fungal Cell Wall Polysaccharides ... 

R673 E. K. Fukuda, A. F. D. Vasconcelos, A. C. Matias, A. De Melo Barbosa, R. F. H. Dekker and M. L. Corradi da Silva, Fungal Cell Wall Polysaccharides Purification and Characterization , Semina Ciencias Agrarias,... 

N. Nwe, T. Furuike, and H. Tamura, Production, properties and applications of fungal cell wall polysaccharides Chitosan and glucan, AdvPolym. Scl, 244,187-207,2011. 

Synthesis of Tailor-Made and Chemically Modified Fungal Cell Wall Polysaccharides with Special Biological Functions... 

C-n.m.r. spectroscopy is useful in monitoring the purity of polysaccharide preparations. Similarly, in a multicomponent, biological system, such as exists in fungal cell-walls, the varying proportion of each polysaccharide can be gauged, once characteristic signals have been identified. 

As with bacteria, fungal virulence factors can be divided into two main categories virulence fectors that facilitate infection and virulence factors that affect the host. Virulence factors that promote adherence to host cells and fecilitate fungal invasion include capsule production to inhibit phagocytosis and cytokines to depress the host immune system. Multiple virulence fectors target the host, such as cell wall polysaccharides that activate the complement cascade and provoke an inflammatory reaction or the secretion of cytokines and mycotoxins that directly damage host tissues. 

Fungal cell walls are composed primarily of the highly crystalline polysaccharides, chitin and )8-glucan, and various nonhydrolyzable melanins (Peberdy, 1990). Section 8.07.5.4 describes the structure and decomposition of chitin. While chitin has been well studied, very little is known about the structure or in situ decomposition of melanins (Butler and Day, 1998). However, melanins are thought to be a possible humus precursor because of their similarities with humic acids (Saiz-Jimenez, 1996). 

Like cellulose (O Sect. 3.1), chitin imparts mechanical strength. Both chitin and cellulose form fibrils. Chitin fibrils are structural elements in the exoskeletons of insects and crustaceans. Fungal cell walls, which often contain 80-90% (dry-weight basis, db) polysaccharide, have been categorized into eight types by polysaccharide composition ... 

A polysaccharide containing A-acetyl-D-glucosamine, which is a major constituent of the fungal cell wall. It is also a major component of the cuticle of an insect. 

Fungal cell walls contain n-alkanes similar to those in the higher plants and possibly fulfilling a similar role. In contrast, waxes are absent in most bacteria. However, the mycobacteria and the related nocardiae and corynebacteria, which contain greater amounts of lipids than other types of bacteria, contain high-molecular-weight waxy molecules in their cell walls (Harwood Russell 1984).These molecules comprise various mycolic acids, such as P-mycolic acid (Fig. 2.15a), which are bonded to polysaccharides and, via phosphate groups, to murein (Fig. 2.9). 

---