Cellulose-hydrolyzing bacteria

The Role of Cellulose-Hydrolyzing Bacteria in the Production of Biogas from Plant Biomass... 

Cellulose-hydrolyzing enzymes are widespread in Fungi and Bacteria. Less thermoactive cellulases have already found various biotechnological applications. The most effective enzyme of commercial interest is the cellulase produced by Tricho-derma sp.[661. Cellulolytic enzymes can be used in alcohol production to improve juice yields and effective color extraction of juices. The presence of cellulases in... 

Digestion can be a limiting factor in the ability of organisms to utilize saccharides. Many adults lack the lactase enzyme required to hydrolyze lactose. When these individuals consume milk products, the lactose remains undigested in the intestine, where it is acted upon by bacteria. These bacteria produce gas and intestinal pain, and diarrhea may result. The lack of a digestive enzyme for cellulose in humans and virtually all other animals means that these animals cannot metabolize cellulose. The cellulosic plant material eaten by ruminant animals such as cattle is actually digested by the action of enzymes produced by specialized rumen bacteria in the stomachs of such animals. 

Molasses, fruit juice, corns, bagasse, Jerusalem artichockes, cassava, whey, sulfite liquor, saw dust and other wood by-products are used as substrates for alcohol and glycerin production. Starch-based substrates should be first saccharified by amylases prepared from barley, fungi or bacteria. Cellulosic materials must also be chemically or enzymatically hydrolyzed before being used as substrates for alcohol production. Clostridium species contain amylases and are able to convert starch and cellulose directly16). 

Humans and other mammals lack the /3-glucosidase enzyme needed to hydrolyze cellulose, so they cannot use it directly for food. Several groups of bacteria and protozoa can hydrolyze cellulose, however. Termites and ruminants maintain colonies of these bacteria in their digestive tracts. When a cow eats hay, these bacteria convert about 20% to 30% of the cellulose to digestible carbohydrates. 

When the diastase of the malt has had time to act the mash is inoculated with a smaller special mash of rye and malt in which a pure culture of lactic acid bacteria (Bacillus delbruckii) is growing. The mash is now incubated for about sixteen hours at the proper temperature (ca. 50° C., 1220 F.). During this time the proteins of the grains are partially hydrolyzed and some lactic acid is formed. The liquor now contains largely sugars, resulting from the action of malt diastase on the starch, lactic acid, amino acids, and other hydrolysis products of the proteins, all in a highly assimilable form for the yeasts, and the cellulose residues from the cereals. 

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