Enzymes cellulose biodegradation

A given microorganism may produce one or more enzymes of each type. An understanding of the role of each enzyme in cellulose biodegradation requires their purification and characterization, and an analysis of the ways in which they interact with the substrate and with each other. However, it is often quite difficult to determine the number and type of truly different enzymes produced by an organism. Many cellulolytic microorganisms secrete proteases, which may degrade some or all of the cellulases to smaller,... 

Biodegradable drilling fluid formulations have been suggested. These are formulations of a polysaccharide in a concentration insufficient to permit a contaminating bacterial proliferation, namely a high-viscosity carboxymethyl-cellulose sensitive to bacterial enzymes produced by the degradation of the polysaccharide [1419]. 

We have chosen to explore enzymes in themK)philic anaerobic bacteria, because these kinds of microorganisms were believed to have been the first forms of life on earth and have evolved under energy limited conditions that place stress on selection of enzymes with high catalytic efficiency (2). Thermoanaerobes contain a diverse array of enzymes with unique properties and their enzyme outfits now serve as models for understanding the biodegradation of polymers such as cellulose (5). 

Plant cell walls are complex, heterogeneous structures composed mainly of polymers, such as cellulose, hemicelluloses, and lignins. In spite of several decades of research, cell wall assembly and the biosynthesis and ultimate biodegradative pathways of individual polymers are still far from being fully understood. One simple example will suffice Even today, no enzyme capable of catalyzing cellulose formation in vitro has been obtained. 

Glasser W., McCartney B., Samaranayake G. Cellulose derivatives with low degree of substitution. 3. The biodegradability of cellulose esters using a simple enzyme assay. Biotechnology Progress 10 214-219 (1994). 

The biodegradation of cellulose is caused by enzymes known as cellulases [471-475]. Cellu-lases are produced by many microorganisms (bacteria and fungi). The most widely studied cellulases are of fungal origin, e.g., Trichoderma [471,473]. The cellulose-digesting bacteria of the rumen are a complex anaerobic community [476,477]. 

The most fundamental classification of polymers is whether they are naturally occurring or synthetic. Common natural polymers (often referred to as biopolymers) include macromolecules such as polysaccharides e.g., starches, sugars, cellulose, gums, etc.), proteins e.g., enzymes), fibers e.g., wool, silk, cotton), polyisoprenes e.g., natural rubber), and nucleic acids e.g., RNA, DNA). The synthesis of biodegradable polymers from natural biopolymer sources is an area of increasing interest, due to dwindling world petroleum supplies and disposal concerns. 

As shown above, in starch the glucopyranoside ring is present in the a-form, while in cellulose the repeating units exist in the P-form. Because of this difference in structures, the enzymes that catalyze the acetal hydrolysis reactions in the biodegradation reactions of each of these two polysaccharides are different for each and are not interchangeable. 

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