Cellulose intestinal bacteria

Suppose human intestinal bacteria were genetically altered so they could hydrolyze the P linkages of cellulose. Would the results be beneficial Explain. 

Non-starch polysaccharides A group of polysaccharides other than starch which occur in plant foods. They are not digested by human enzymes, although they may be fermented by intestinal bacteria. They provide the major part of dietary fibre. The main non-starch polysaccharides are cellulose, hemicellulose (insoluble non-starch polysaccharides) and pectin and the plant gums and mucilages (soluble non-starch polysaccharides). 

The general name given to an enzyme which breaks down cellulose. Cellulases are present in certain intestinal bacteria and in various other microorganisms such as those which inhabit the digestive tract of grazing animals (cattle, goats, and sheep). 

Humans lack enzymes to hydrolyse cellulose, and some odier carbohydrates in food. However, bacteria in the intestine can hydrolyse and ferment some of this carbohydrate to produce short-chain fatty acids, which are used by the colon and the liver. It is estimated that for each gram of unavailable carbohydrate in the diet, 8.4 kJ of energy is made available in this way, although this is influenced by factors such as ripeness of fruit or the way leguminous seeds are cooked. Nonetheless, these effects will be small and can be ignored unless the amount of such carbohydrate is high or very accurate results are required. (The subject of unavailable carbohydrate and fibre in the diet is discussed in Chapters 4, 6 and 15). 

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. 

Over millions of years, some animals evolved a specialized pouch in their digestive tracts to house these bacteria. This pouch—a fermentation sac—can either be located at the front end of the digestive tract, where it is called the rumen, or at the far end of the digestive tract, where it is called the large intestine or cecum. In these fermentation sacs, the cellulolytic bacteria happily do their thing and in turn, produce nutritional products that can be absorbed and used by the host animal for its own metabolism. Thus the ruminant or horse or alpaca or any animal housing these bacteria (including, to a small extent, humans) can obtain nutritional value from cellulose. 

Babendreier D, toiler D, Romeis J et al (2007) Bacterial community structures in honeybee intestines and their response to two insecticidal proteins. FEMS Microbiol Ecol 59 600-610 Bae S, Fleet GH, Heard GM (2006) Lactic acid bacteria associated with wine grapes from several Australian vineyards. J Appl Microbiol 100 712-727 Barak ID, Jahn CE, Gibson DL, Charkowsky AO (2007) The role of cellulose and O-antigen capsule in the colonization of plants by Salmonella enterlca. Mol Plant Microbe Interact 20 1083-1091... 

Many bacteria, fui, and Actinomyces produce cellulolytic enz5mies. Most higher animals cannot metabolize cellulose, but herbivorous vertebrates, whose intestinal flora contain ceUulose-splitting anaerobic bacteria make use of cellulose indirectly in this manner. Actinomyces species are mainly responsible for the aerobic breakdown of cellulose in the soil, while many fungi will attack wood and utilize its cellulose metabolically. 

Oligosaccharides are not digested by the human gastro intestinal enzymes, and are passed intact into the large intestine where they are fermented by the colonic bacteria. Some disaccharides such as maltose and cellobiose can be prepared through hydrolysis (chemical or enzymatic) from starch and cellulose, resp. (Hirayama, 2002 Collins Rastall, 2008), while higher oligosaccharides, e.g., hexa-, hepta- and nona- saccharides, have been obtained... 

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