Bacteria celluloses from

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). 

Other commercial sources of cellulosic fibers include hemp, jute, flax (linen), and ramie. Wood fibers are used in papermaking and as a feedstock for rayon. Of these sources, cotton provides the purest cellulose. From an experimentalist s point of view, algae and even animals (the tunicates) are also interesting sources of cellulose. Bacteria such as Acetobacter xylinium make extracellular cellulose, but in higher plants and algae, cellulose occurs in the walls of individual cells. 

B. G. Ranby, Inst. Phys. Chem., Univ. Uppsala, Arkiv Kemi, 4, 241 (1952). Fine structure and reactions of native cellulose. Electron microscope study of morphology of celluloses from wood, cotton, bacteria, tunicates, and algae behavior of samples on swelling in sodium hydroxide and hydrolytic degradation. 

Figure 4.3.1 Schematic representation of the enzymatic degradation of starch from plants, fungi and bacteria, and cellulose from plants, (o), Reducing glucosyl residues ending with a half-acetal unit ( ), nonreducing glucosyl residues corresponding to full ac-etals f—), crystalline regions of cellulose ( ), amorphous regions of cellulose. (From Kennedy, 1988.)...

As soon as it is involved in a glycosidic link, it is locked into one form or the other. Starch has one form (alpha linkage) and cellulose the other (beta), and enzymes will discriminate absolutely between the two. So we cannot digest cellulose. Even cows cheat because it is not their enzymes that break down the cellulose from grass, but the tanks of bacteria they carry with them ... 

Not all animals obtain the essential amino acids from plants. Some (the ruminants) can by-pass the main route by direct assimilation of the amino acids produced by symbiotic bacteria in the gut. These bacteria can break down cellulose, the main structural carbohydrate of plants, and can also synthesise all the amino acids, required for their growth and development, from a simple fixed-nitrogen source. The ruminant obtains its more complex nitrogen requirements by digestion of dead bacteria. (Goats, for example, can survive on a diet of hay and ammonia.) This may appear to be a somewhat one-sided symbiosis, with the bacteria carrying out all the important functions but, in return, the bacteria obtain from the animal a copious supply of carbohydrate and are maintained in a favourable environment with respect to temperature and medium composition. 

The biosynthetic pathway that produces bacterial cellulose from glucose and fructose is shown in Fig. 14.2. Glucose is phosphorylated by glucose hexokinase and not by the phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS). The resulting glucose-6-phosphate (G6P) is metabolized through the pentose pathway, because the activity of fructose-6-phosphate (F6P) kinase, which phos-phorylates F6P to fructose-1,6-diphosphate (FDP), is absent in acetic acid bacteria. 

Elberson MA, Malekzadeh F, Yazdi MT, Kameranpour N, Noori-Dloii MR, Matte MH, Shahamat M, Colwell RR, Sowers KR (2000) Cellulomonaspersica sp. nov. and Cellulomonas iranensis sp. nov., mesophilic cellulose-degrading bacteria isolated from forest soil. Int J Syst Evol Microbiol 50 993-996... 

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