Cellulose degrading enzymes, fungi producing

Basidiomycetous wood-decay fungi produce cellulose-degrading enzymes of two principal types. Endocellulases hydrolytically split the long cellulose chain randomly, thereby producing many short cellulose chain fragments of varying... 

As referred previously, two main types of cellulolytic systems are currently recognized. Those based on free , soluble enzymes, produced mostly by aerobic microbes that secrete individual cellulases, which act synergistically on native cellulose and those based on complexes of cellulolytic enzymes, or cellulosomes , produced by some anaerobic bacteria and fungi, which are usually attached to the outer surface of the microorganism [40, 101]. CBMs play a role in the phase transfer of a soluble free enzyme onto the insoluble substrate [68, 69]. CBMs are present in several polysaccharide-degrading enzymes, namely in hemicellulases [56, 58, 102], endomannanases [12], xylanases [56, 103], acetyl-xylanesterases [104] and )3-glucosidases [71]. 

Many fungi are capable of producing extracellular enzymes that can degrade cellulose. They are Trichoderma (T) reesei, T. viride, T. koningii, T. lignorum, Penicillium funiculosum, Fusarium solani, Sclerotium rolfsii, and so on. Bacterial species such as Cellulomonas along with Clostridium thermocellum can also produce cellulases (Marsden and Gray, 1986). 

Cellulose Cellulose is a straight-chain polymer of glucose units linked by (31-4 bonds. The polysaccharide chains are aligned to form fibrils that have great tensile strength. Cellulases, enzymes that degrade cellulose, are absent in mammals but are produced by some bacteria, fungi and protozoa. 

Cell walls are biochemically rather inert with reduced digestibility to many organisms because of their complex cellulose, pectin, and lignin molecules. Callose and lignin are often accumulated at the site of infection or wounding (6,7) and form a penetration barrier. Synthesis of inhibitory proteins (e.g., lectins, protease inhibitors) or enzymes (e.g., chitinase, lysozyme, hydrolases, nucleases) that could degrade microbial cell walls or other microbial constituents would be protective, as well as synthesis of peroxidase and phe-nolase, which could help inactivate phytotoxins produced by many bacteria and fungi. These proteins are either stored in the vacuole... 

Hydroxyethyl cellulose is subject to enzymatic degradation, with consequent loss in viscosity of its solutions. Enzymes that catalyze this degradation are produced by many bacteria and fungi present in the environment. For prolonged storage, an antimicrobial preservative should therefore be added to aqueous solutions. Aqueous solutions of hydroxyethyl cellulose may also be sterilized by autoclaving. 

Most bacteria are incapable of degrading crystalline cellulose since their cellulase systems are incomplete. However, the cellulolytic enzymes produced by some fungi generally involve all three types of enzymes, so they are very useful in the saccharification of renewable cellulosic resources. 

Many fungi are capable of producing extracellular enzymes that can degrade cellulose. They are Trichoderma (T) reesei, T. viride, T. koningii,... 

Many fungi are cellulolytic (1, 2, 6, 16, 39, 40), and most of these produce cellulase when grown on cellulose. However, only a few produce culture filtrates that extensively degrade solid cellulose. Over the years, we and many others have compared thousands of microorganisms for their ability to degrade cellulose and hundreds for their ability to produce cell free enzymes that can be used to hydrolyze cellulose. In general, the enzyme containing filtrates are rather inactive when one... 

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